A new and versatile 3D printed on-chip integration approach with laser machining is demonstrated in this paper for microwave and mm-wave systems . The integration process extends interconnects laterally from a MMIC to a chip carrier. Laser machining techniques are studied and characterized to enhance the 3D printing quality. Specifically, the width of micro-dispensed printed traces is accurately controlled within micrometer range and probe pads are formed by laser cutting to facilitate RF measurement. S-parameters of a distributed amplifier integrated into the package are simulated and measured from 2 to 30 GHz. The overall performance is significantly better than traditional wirebonded QFN package. The attenuation of the microstrip line including interconnects is only 0.2 dB/mm at 20 GHz and return loss with the package is less than 10 dB throughout the operating frequency band

This paper proposes a rapid-prototyping method for low-loss millimeter-wave hollow waveguides using 3D printing technology. Waveguide models are modified to enhance their mechanical strength, 3D printed with a light-weight photopolymer using a Digital Light Projection (DLP) method. A modified version of copper electroless plating is then used for metallization to achieve very low loss at millimeter waves. To demonstrate, 3D printed waveguides are fabricated for W-band and D-band. The measured insertion loss is between 0.12 dB/in to 0.25 dB/in over the entire W-band, as the best loss performance when compared reported W-band 3D printed waveguides, to the best of authors’ knowledge, and between 0.26 dB/in to 1.01 dB/in over the entire D-band. These results are comparable to commercially-available metal waveguides and show great promise for manufacturing more complex geometries with this technique.

Additive manufacturing allows for fabrication of complex structures that efficiently use a 3D volume of space. Current state of the art metal additive manufacturing methods, particularly Selective Laser Melting (SLM), allow for intricate parts with high mechanical strength but at the cost of increased surface roughness on internal walls. This paper investigates the contribution to loss of the increased surface roughness on a set of SLM WR42 waveguides printed with a standard ALSi10Mg aluminum powder, and compares their attenuation performance to purchased single-piece WR42 waveguides and to an industry-standard method for CNC machining waveguide multi-piece assemblies. Single-piece construction of RF parts produces lower attenuation than multi-piece assembly, and lower surface roughness directly leads to lower attenuation. SLM RF waveguides had better part consistency and comparable or better attenuation compared to CNC waveguides, showing that SLM has reached the point where it can be used in RF waveguide assemblies.

This work reports on the integration of RF functionalities in microwave waveguide components through the selective laser melting process. A specific integrated component has been developed for the relevant application domain of satellite communications. The component operates in the Ku-K bands and integrates a H-plane bend, a 90-deg twist and ninth-order pass-band filter. The AlSi10Mg prototype manufactured through selective laser melting exhibits significant RF performances (return loss > 20 dB, insertion loss < 0.23 dB, and rejection > 60 dB), while significantly minimizing mass, envelope and mechanical complexity.

This paper presents several W-band (75-110 GHz) WR-10 waveguide components fabricated using both direct metal laser sintering (DMLS) and stereolithography (SLA), in aluminum, nickel and copper alloys and metal-coated plastic (MCP). The RF performance and surface roughness are measured, and the loss due to surface roughness quantified. The measured loss at 95 GHz ranges from 0.055 dB/cm for the copper-plated plastic waveguides to 0.37 dB/cm for the nickel alloy. From a loss budget study, it is found that standard models do not accurately predict loss due to surface roughness for very rough surfaces. This paper presents the current state-of-the-art in available additive manufactured (AM) waveguide components at W-band.

This paper compares two radar configurations with different antenna systems for measuring particle streams in the near field range. A complex source beam is employed to describe the field characteristics. This new approach is used to derive the associated antenna gain and power patterns and applied in the radar equation for particle streams. We demonstrate how indoor measurements benefit from a bistatic radar configuration and provide measurement results for streams with particles in the micron range.

A 77-GHz Doppler shift radar is demonstrated based on an Active Quasi-Circulator (QC) monostatic approach. The QC system includes a leakage canceler as well as a modulator for time division IQ switching. A flexible decimation chain, implemented in an FPGA, facilitates the use of a low cost ADC with poor SNR performance. By analyzing the drift behavior of the system, the parameters for an appropriate high pass filter can be obtained. The system is capable of measuring Doppler shift frequencies from 0.05Hz up to around 4 kHz. By means of a phase evaluation algorithm, it is possible to observe objects with varying velocities. Finally, the system has been verified with a breathing test, where the depth and the frequency of the breath can be determined accurately.

This paper presents a Ku-band (14-16 GHz) CMOS frequency modulated continuous-wave (FMCW) radar transceiver developed to measure snow depth for water management purposes and to aid in retrieval of snow water equivalent (SWE). An on-chip direct digital frequency synthesizer (DDFS) and digital-to-analog converter (DAC) digitally generates the chirping waveform which then drives a ring oscillator based Ku-Band phase-locked loop (PLL) to provide the final Ku-band FMCW signal. Employing a ring oscillator as oppose to a tuned inductor based oscillator (LC-VCO) allows the radar to achieve wider chirp bandwidth resulting in a higher axial resolution (7.5cm) which is needed to accurately quantify the snowpack profile. The demonstrated radar chip is fabricated in a 65nm CMOS process, and it consumes 250mW of power under 1.1V supply, making its payload requirements suitable for observations from a small UAV.

In this paper, the integration of a communication link for a modulated-reflector radar is presented. This kind of radar system is intended to determine the position of multiple semi-passive backscatter reflector nodes, designed to be mounted on different objects of interest. A method to transport information from these objects back to the radar-basestation is sketched, using the available hardware-resources of the nodes. In addition a technique minimizing the influence of this communication link on the localization capability of the system is presented and validated by measurements

High-speed communication systems nowadays often face technological limitations, e.g., when operating at very high center frequencies. These scaling issues often result in low single-stage amplifier gain, which makes classic broadband communication architectures, most notably the homodyne transceiver, inefficient in terms of power consumption, implementation size and cost. For the first time, we demonstrate the feasibility of a full transmission system for a completely different architecture that allows escaping the gain limitations. It utilizes regenerative sampling in an oscillator to repetitively amplify CW or pulsed signals with a single low gain amplifier in order to achieve a high overall gain tunable over a large range. In this paper, we demonstrate the successful transmission of 8-PSK modulated pulsed signals with a data rate of 450 Mbit/s at 5.6 GHz and verify that phase regeneration from pulses generated by free running oscillators has no notable SNR drawback compared to classic systems.

A novel series-stacked large swing push-pull MOSHBT driver was implemented in SiGe BiCMOS. The circuit achieves 4.8Vpp differential swing, 57.5GHz bandwidth and has an output compression point of 12 dBm per side. 4-PAM and 8-PAM eye diagrams were measured at 56 GBaud for a record data rate of 168 Gb/s. 4-PAM 64Gbaud eye diagrams were also demonstrated, The circuit consumes 820/600 mW with/without the predriver, for an energy efficiency of 4.88/3.57 pJ/b.

A 128-GS/s 63-GHz-bandwidth 2:1 analog-multiplexer (AMUX) module has been developed for ultra-broadband digital-to-analog (D/A) conversion subsystems. The AMUX IC was fabricated using 0.5-μm-emitter InP HBTs, which have a peak ft and fmax of 290 and 320 GHz, respectively. The IC has a through bandwidth of 67 GHz. We developed an ultra-low-loss metal package equipped with G3PO (SMPS) connectors. The AMUX module based on our new package has a through bandwidth of 63 GHz and operates at a sampling rate of up to 128 GS/s. We then constructed an over-50-GHz-bandwidth D/A conversion subsystem based on two 26-GHz-bandwidth sub-DACs and this AMUX module. In addition, we successfully demonstrated a 214-Gb/s discrete multi-tone (DMT) signal generation.

A broadband high-speed high-linearity track-and-hold amplifier (THA) is presented in this paper using 0.18 μm SiGe process. A switched emitter follower track-and-hold (T/H) stage with cas-code stage is adopted to achieve high resolution for analog-to-digital conversion. A modified Darlington amplifier with peaking technique is used to enhance the input bandwidth. With a dc power consumption of 94.3 mW, the proposed THA demon-strates a 3-dB input bandwidth from DC to 27 GHz, a maximum spurious-free dynamic range of 45 dB, and a minimum total harmonic distortion of -40 dB. The proposed circuit has potential for high-speed high-dynamic-range applications due to its supe-rior performance.

An 80 Gbps 2^{15}-1 pseudo-random bit sequence (PRBS) generator offering a unique feature of two programmable channels is presented. It is possible to select either a replica of the full rate stream, two parallel streams at half the rate, or a combination of external and internal pattern to the output. This flexibility makes the design suitable for generating proper test signal for both binary and 4-PAM (pulse-amplitude-modulation) communication systems. While the longer sequence in this design adds to the complexity, the energy per bit is comparable with the state-of-the-art designs. Notably for the clock drivers, as one of the bottlenecks of a PRBS generator, an open-collector structure with distributed loading is studied and optimized for very low power operation. The design features a clock divider and zero detection circuit as well. The circuit was fabricated in a 130 nm SiGe BiCMOS process (300/500 GHz f_T/f_{max}).

In this paper it will be shown that cascading Delta-Sigma Modulators with different sampling rates can have a considerable impact in relaxing the high quality factor of the analog output filter used in All-Digital Transmitters. In particular, a significant reduction of the noise peak power can be achieved with just minor changes in the hardware. This novel concept has been successfully implemented and validated on an FPGA-based transmitter, and compared with the conventional architectures that perform a single-bit quantization into a single stage.

An FPGA-based all-digital transmitter with 9.6-GHz 2nd order Time-Interleaved ΔΣ-modulation (TI-DSM) is presented. To improve the operation frequency of TI-DSM, bit separation architecture is proposed. This proposed architecture realizes the 1-bit digital transmitter with 500-MHz bandwidth. This is the widest bandwidth modulation among state-of-the-art FPGA-based all-digital transmitters.

In this paper, we present a novel architecture for an All-Digital FPGA-based Antenna Array RF Transmitter. The proposed method reduces the complexity inherent to the design of antenna arrays by removing external Digital-to-Analog Converters and external analog upconversion stages. With such a concept, the analog front-end complexity is highly reduced and, consequently, more radiating elements can be integrated. This novel concept has been successfully validated with an FPGA-based transmitter. Normalized radiation patterns as well as Error Vector Magnitude measurements were obtained for different steering angles. A minimum steering resolution of 1º was achieved with a low-complexity baseband phase shifting procedure. In addition to that, an automated calibration procedure is also presented and evaluated.

In this paper, we present a 3 GHz biphasic RF power harvesting system for biomedical wireless implantable applications. The design includes an on-chip loop antenna, a six-stage voltage rectifier, a low dropout voltage regulator, a power management unit (PMU), and an array of low-noise differential amplifiers for sensing bio potentials. The system is fabricated in a 180 nm SOI CMOS technology with a total area of 1.6×1.6 mm2 including an on-chip 1.2 nF storage capacitor. A power management unit with an average current consumption of 10 nA, which is 8× smaller than the state-of-the-art, divides the operation of the system into two different phases. The system is capable of delivering 1.21 mW to an external load that is fed by an on-chip voltage regulator.

A highly-integrated CMOS power-management system with wide-range RF for ultra-high frequency (UHF) wireless energy harvesting is presented. To avoid environment-caused sudden power loss and to scavenge energy efficiently, the proposed power management system adopts power-aware rectifier architecture and adaptive DC-DC conversion ratios according to the input power level. The proposed system was fabricated in a 0.18-μm CMOS process. The system achieved a peak RF/DC conversion efficiency of 59%, a sensitivity of -11.6dBm, and a 13.5dB RF input range for at least 20% power efficiency at a 100KΩ load. At the high input power region (>-9dBm), the proposed architecture improves to about 15% efficiency when compared to a conventional rectifier followed by a linear regulator. The peak efficiency of the entire system is 37%.

An innovative topology for W-band energy harvesting is proposed using 65-nm CMOS, including an on-chip antenna. The rectifying circuit is based on inverse operation of a differential Colpitts VCO and a loop on-chip antenna is coupled to the rectifying circuit. Occupying total area of 0.611 mm2, the harvester has a peak output power of 0.2mW with an efficiency of 6%, while the rectifier circuit itself achieved a measured efficiency of 21.5%. Implementing a 3x3 array of CMOS rectennas on a PCB enabled a x3.5 increase in harvested power at 95GHz.

This paper reports a 2.48 GHz tri-coil and rectifier design implemented in a system that demonstrates simultaneous wireless power transfer and communication to a 0.1 mm by 0.1 mm coil. The tri-coil link and rectifier successfully rectified and demodulated a 20 dBm amplitude-shift keyed (ASK) RF signal modulated at a rate of 1 Mb/s. Additionally, a 5.7 GHz tri-coil link was fabricated to validate the frequency scalability of this technology platform for other unlicensed bands and was measured in a customized experimental testbed to account for the effects of lateral misalignment between coils. The 5.7 GHz tri-coil design had a measured peak RF power transfer efficiency of -29 dB with a vertical separation of 1 mm, which is ten times the load coil diameter.

This paper presents a fast response wireless power delivery system with open loop dynamic transmitter voltage scaling technique to keep power efficiency in wide load range. In this technique, according to changing power consumption required in the receiving side, the driving voltage of the transmitter (TX) coil is properly adjusted for controlling transmission power. The transmitting power and switching loss can be reduced in proportion to the square of the driving voltage. Therefore, it can prevent decrease in power efficiency. To promote power control speed, the driving voltage is not locally regulated but automatically determined by the feedback loop of the total WPT system. The fabricated test chips in 180-nm LDMOS process achieved maximum power efficiency of 50.2% when the output power is 0.54W.The output power ranges from 0.03W to 0.54W. The ripple is kept within 3.5% even when the output power is abruptly changed by one order of magnitude.

A 915 MHz GaN HEMT-based Class-E rectifier is proposed in this paper to be used for DC+AC wireless power recovery. Taking advantage of the time reversal (TR) duality principle, the rectifier was derived from a Class-E inverter, whose output network was designed for high-efficiency operation over a wide range of resistive loads. The addition of an appropriate gate-side termination allows the device to be turned-on without an additional RF source for gate driving. The rectifier reduced sensitivity to load variation, as well as its capability for efficiently and linearly recovering the envelope of an AM RF excitation, were then characterized. An average efficiency of 82% has been measured for the combined RF-to-DC and RF-to-AC power conversion of a 1.6 W modulated carrier. Frequency multiplexing and frequency modulation alternatives for high-level DC+AC wireless power transmission are finally presented.

A 2.4GHz-band high power and high efficiency in-jection-locked oscillator has been developed for use in the mi-crowave ovens having uniform heating as well as subtle tempera- ture control. With the use of the imbalanced coupling resonator in the feedback circuit, an output power of 210W and an efficien-cy of 51% have been successfully obtained at 2.45GHz, where a reference signal of less than 1/10,000 has been injected. The high power and high efficiency solid-state injection-locked oscillators presented in this paper has an advantage in long life, frequency and phase controllability, and low voltage operation, which can be useful for realizing an accurate temperature control in chemi-cal reactions as well as the spot and uniform heating of micro-wave ovens.

An injection-locked magnetron was investigated at low power injection. The 1 kW magnetron has been locked over the ratio of the input power to output power of -57 dB. It is much less than the required injection power in previous experiments. The purity of spectrum was presented. The phase noise of the locked magnetron was less than -93.1 dBc/Hz at 10 kHz offset. The oscillation spectrum has FM noise due to the spurious of input reference signal and injection locking contributes to reducing the FM noise itself to some extent. The injection locking technique may be applied to power combining or large-power amplifiers based on magnetrons.

An X-band radial power combiner based on an airline coax with 0.15 dB measured insertion loss, 8 dB minimum port-to-port isolation, 33% bandwidth, and the ability to handle kilowatt power levels is presented in this work. The design can readily be scaled to arbitrary frequencies or any number of ports. The methods used to select the parameters and optimize the design are presented. The models are validated by a 9-port X-band proof-of-concept combiner.

The use of heat exchangers to harness microwave energy has great potential in transmitting and collecting beamed energy through space. We consider a simple three-layer laminate model in which a middle layer characterized by a temperature-dependent loss factor is surrounded by two lossless dielectric layers. It is shown that when plane waves, symmetrically impinging the laminate at normal incidence is applied, conditions analogous to Bragg interference occur for a fixed loss factor in the middle layer. For the loss factor depending on temperature,we find a new stable steady-state solution corresponding to resonance conditions, whose equilibrium temperature is significantly elevated but prevents the onset of thermal runaway. The impact of this result on transferring harnessed microwave energy to other media is discussed.

The first-ever reported Gbps backscatter trans- mission is presented at millimeter-wave frequencies, extremely expanding the potential of backscatter radio as a low-energy, low-complexity communication platform. Minimal front-ends are implemented that can be used for multi-gigabit communication and RF sensing, achieving scattering frequencies of at least 4 GHz away from a carrier center frequency of 24 GHz. The significantly wideband operation of these minimal communicators will enable broadband wireless transmission with less than 0.15 pJ/bit front- end energy consumption at 4 Gbps and sensing with an extensive number of low-power sensors. The front-ends are additively manufactured using inkjet printing on flexible substrates that can be directly integrated with wearables for challenging mobile applications in 5G and the Internet of Things (IoT).

This paper reports for the first time a long-range interrogation (> 50 meters) of wireless and batteryless humidity sensors combining a Van-Atta retrodirective array and a 3D beam scanning using a 24GHz Frequency-Modulated Continuous-Wave radar. Van-Atta cross-polarization properties, as well as the use of dedicated statistical estimators and Synthetic Aperture Radar technique allow the long-range measurement of the relative humidity at a distance of 58 meters. A measurement sensitivity of 0.2dB to 0.4dB per %RH was measured as a linear variation of the proposed estimator with a standard error of ±0.005dB.

This paper presents a fully passive wireless sensor based on a single E-pHEMT device. The implemented circuit behaves as a RF to DC rectifier when the gate of E-pHEMT is unbiased and as a modulator when the generated voltage is 0.6 V. The sensor achieves 83% efficiency for 16 dBm of input power and it is demonstrated that for higher powers the backscatter modulator has a very good behaviour.

This paper presents a low-cost self-powered UHF RFID tag-based sensor. The proposed tag-based sensor comprise a miniaturized dual-feed loop tag antenna incorporated with multiple RFID chips and a resistive sensor for utilizing reference and sensor nodes. One RFID chip is integrated in the reference node transmitting in the sensing process, and another one with integrated sensor (sensor node) transmits a signal impacted by the sensed data. By measuring the power ratio of the required minimum power transmitted by the reader to wake-up the RFID chips in both the reference and sensor nodes, the reader then can extract the sensed data i.e. temperature. The miniaturized RFID tag-based sensor is fabricated and experimentally evaluated. The measured results demonstrate that the developed miniaturized dual-feed tag-based sensor can be integrated with resistive sensor for low-cost wireless sensor nodes.

We characterize textile antennas and antenna-electronics inter-connections created by depositing conductive paint and by em-broidering with conductive yarn. Both approaches are based on affordable materials and enable single-step manufacturing of RFID tag on textiles. To achieve further material savings, our dipole antennas comprise of line-type structures instead of the commonly used metallized surfaces. To understand the electro-magnetic properties of the antennas in and to assess the quality of the conductors, both wireless measurements and electromag-netic field simulations were used. Overall, the tags made of the conductive yarn by embroidering were detectable at the dis-tances of 5-to-6 meters in air and at 2 meters on the human body. Conductive paint yielded the corresponding distances of 3.5-to-4 meters and 1 meter, respectively.

Planar W-band antenna tiles were created by defining pixelated subwavelength metal patterns on 4 mm square and 500 micron thick glass tiles space fed by an open ended waveguide. The metal patterns were optimized to form beams and convert polarization. The metal patterns were found by genetic algorithm optimization of finite difference time domain simulations. Several antennas were fabricated, measured, and found to agree with the predictions.

A dual-polarized frequency-scanning phased-array antenna based on composite right/left handed (CRLH) feed network is presented. The proposed feed network provides phase advance in addition to phase delay and allows uniform power distribution to each antenna element, thereby delivering high directivity frequency-scanning radiation beams that can scan the full-hemisphere.The working mechanism is presented through a broadband microstrip antenna. The orthogonally placed feed networks and coupling slots enable the dual-polarized (horizontal/vertical) operation of the proposed antenna array without compromising the high isolation between two feeding ports. Full space frequency scanning capability for both polarization states are verified experimentally.

This paper presents a novel sequential transmitter phased array architecture for efficiency boosting of the transmitter-receiver link. The boost in efficiency is achieved by transmitting the signal peaks and the remaining data through different chains, each of which optimized for specific power, and recombining the signal over-the-air. Experimental results verified the over-the-air com-bining concept in actual environment. An 80 MHz 802.11ac OFDM signal with 9.7dB PAPR at 5.5GHz was transmitted through an array of 4 patch antennas. The received EVM was lower than -38dB, similar to a uniform excited array. Simulations show that this transmitter can boost the efficiency by 31% and 54% for 8dB and 10dB power back-off from the array maximum power respectively, without any penalty in die area nor antenna size compared to a uniform array.

A 320 GHz on-chip 2 × 2 antenna array employing a compact feeding network is presented in this paper. The feeding network is designed based on the conducted-back coplanar waveguide (CBCPW) transmission line with a compact size, which has the full shielding performance providing good isolation from circuits around or below the CBCPW transmission lines. The proposed on-chip feeding network and antenna array are fabricated using standard 0.13-μm SiGe process. The antenna array is measured using a specially designed backside radiation measurement system. The simulated and measured results show that the backside radiation on-chip antenna array has a measured peak gain of 7.9 dBi at 320 GHz.

In this paper, a hybrid antenna is proposed for full-duplex system. The antenna is utilized a single slot for resonance, and the length is designed as 3/4 λ0 to generate a short circuit at the other port. Therefore, two parallel transmission lines could be extended across the specified slot design and individually con-nected with two equal length open stubs for impedance matching. After the design optimization, the RF bandwidth is from 24 to 25 GHz, and an isolation 58 dB at the center frequency of the system is achieved by using liquid-crystal polymer (LCP) material for low loss. The front-end module with wire bonding assembly is also considered in 3D simulation. Index Terms—slot antenna, duplexer, full-duplex system, high isolation, liquid-crystal polymer.

This paper proposes a low profile wideband pattern reconfigurable stacked patch antenna, which is composed of four antenna elements. Each antenna element has two switchable feeding ports. Individual excitation at the two feeding ports can produce a 180° phase-shifting due to the symmetrical structure. A reconfigurable 2×2 prototype is developed by employing four single-pole double-throw (SPDT) switches. By properly selecting the feeding ports for the four antenna element, the 2×2 antenna array can generate four beams including sum beams, difference beams in XOZ and YOZ planes and bi-difference beam. The measured 10-dB impedance bandwidths are 5.18-6.01 GHz, 5.17-6.24 GHz, 5.17-6.23 GHz and 5.18-6.24 GHz for the sum, x-difference, y-difference and bi-difference beams, respectively.

A novel wideband decoupling technique for closely-spaced two-element MIMO antenna array is proposed. Wideband and high port isolation is achieved by the creation of two independently controlled transmission zeros (S_21=0) at appropriately selected frequencies. Simulated and measured results show that the proposed method can offer port isolation enhancement of > 20 dB over a fractional bandwidth of almost 20%.

The paper presents the design, and measurement results of a new millimeter-wave Dielectric Resonator Antenna (DRA) array implemented in high resistivity Silicon Image Guide (SIG) technology. The proposed SIG antenna offers a low-cost, and high gain DRA array concept for millimeter-wave applications. The design includes a low loss SIG power splitter which has been used to feed the 4-by10 antenna array. The antenna with the feed has a measured return loss better than -10dB within the frequency range from 90 GHz to 110 GHz. The measured gain is 19 dB at 97 GHz. The measurements data are in good agreement with the simulation results. A single mask dry etching process has been used to realize the proposed antenna. A group of narrow non-radiative supporting beams are designed to enhance the structure mechanical stability.

This paper presents a high-throughput flow cytometry in CMOS for single-cell deformability analysis. By applying hydrodynamic stretching using microfluidics, cells are compressed and deformed depending on its elasticity. A CMOS 11-GHz dielectric sensor with on-chip coplanar electrodes is used to measure the degree of deformation through changes in the capacitance encoded in the measured waveforms. Experiments using polystyrene beads and THP-1 cells with and without ethanol incubation demonstrate the system capability with a throughput greater than 1 kcells/sec.

This paper describes the relative permittivity extraction of cells submitted to different stimuli by using a microwave biosensor, specifically developed to analyze single cells in their culture medium. The sensitive part of the device is constituted by a 5 μm coplanar gap, over which the cell is blocked by a mechanical trap. It allows to obtain the capacitive and conductive contrasts of a cell. Electromagnetic simulations where the cell (sphere) permittivity is tuned permit to define fitted calibration curves linking capacitive and conductive contrasts to the real and imaginary parts of the relative permittivity. Measurements are performed over various cells (in their culture medium) after different environmental stimuli in order to induce various biological stresses altering the cell state. Results show that this non-invasive technique, including the developed proper de-embedding post-process, provides the intrinsic dielectric image of single biological cells, which then reveals their biological state.

Traditionally, electroporation of biological cells is tracked by fluo-rescence microscopy with chemical dyes that tend to be slow and invasive. This paper reports, for the first time, electroporation tracked by real-time change in the microwave insertion loss, which is correlated with simultaneous change in cell morphology recorded through an optical microscope. The change in insertion loss was found to be faster and more abrupt than the change in cell morphology, although the latter was still faster than fluores-cence microscopy. Although more work is needed to verify whether these changes correspond to a reversible electroporation or not, the present result suggests that real-time microwave char-acterization can be a faster and less invasive technique for early detection of electroporation. Additionally, although the electro-poration is presently performed on Jurkat human lymphoma cells, it is believed that the same technique can be extended to many other types of cells.

We employed dielectrophoresis (DEP) to investigate changes in the dielectric properties of single Chinese hamster ovary (CHO) cells induced by nutrient depletion. CHO cells were concurrently incubated in media with and without glucose and glutamine. After 54 hours, cells were identified as viable and non-viable by trypan-blue exclusion test. The DEP response of single viable and non-viable cells were measured at frequencies over a 100 kHz-300 MHz frequency range using a wide-band DEP cytometer. The results reveal that the induced stress is accompanied by decrease in the ion the content of cytoplasm, decline in cytoplasm permittivity, and decrease in the cell membrane capacitance.

In this paper, a microwave non-invasive blood glucose monitoring system is designed and its performance in terms of accuracy and repeatability is evaluated by a clinical trial involving 24 human subjects with and without diabetes. Direct comparison with the most accurate bench-top commercial glucose analyzer shows the exceptional accuracy and repeatability of the proposed microwave non-invasive blood glucose monitoring system.

This study combines self-injection-locked (SIL) radar and ILO-based phased array to conduct non-contact vital sign detection on multiple users. For this purpose, multiple injection-locked oscillators (ILOs) are mutual injection locked to each other at a common frequency. By adjusting the tuning voltages of ILOs, the phase shift among ILOs can be controlled, and therefore the beam scanning of the array can be achieved. Moreover, the signals reflected from the chest of the subjects are injected into the ILOs to enter an SIL state for radar operation. In the experiment, the prototype operating in the 2.4-GHz ISM band is utilized to detect the vital signs of three subjects within two meters at different azimuth angles relative to the array.

This paper presents a self-injection-locked (SIL) radar system to transmit and retransmit (T&RT) a continuous wave to the opposite sides of a human body to detect vital signs with large body movement cancellation. The system can reduce the nonlinear effects caused by body movement on the vital sign signals in the process of cancelling the body motion artifacts. Moreover, a tunable phase shifter is used to improve the limitation of this system due to the environmental clutter. In the experiments, over 95% of the body motion artifacts are removed in real-time monitoring of the vital sign signals when the body moves over a range of more than a wavelength.

A Digital IF Phase-Tracking Doppler radar is presented for accurate displacement measurements and vital signs monitoring. This novel architecture implements a digital Phase-Locked-Loop (PLL) in phase demodulator configuration to extract the phase modulation caused by a moving target without requiring the small-angle approximation condition and solving the null-point issue. This facilitates the accurate measurement of a target’s motion. Experimental results successfully demonstrated the feasibility of the proposed approach.

The accuracy of physiological displacement measurement with CW Doppler radar is affected by the performance of DC offset cancellation. This paper presents an arc shifting approach to improve Levenberg-Marquardt (LM) method that is widely used for such calibration. The LM method becomes less accurate when measured displacement is very small with respect to carrier wavelength. An experiment was conducted in measuring dis-placement of 2 mm and 1 mm using 2.4 GHz quadrature continuous wave (CW) Doppler radar, which demonstrated at least 35% improvement in accuracy when arc shifting method is applied.

A double sideband continuous wave (DSCW) radar for the moni-toring of artery wall movements has been designed and realized. The radar is based on a transceiver, a coherent demodulator and a bow-tie antenna. A feasibility study suggested the 1-3 GHz band as the most suitable for the proposed application. The DSCW radar has been simulated with the microwave office CAD and has been implemented with discrete components. Responses measured on the realized radar are in good agreement with simu-lations. When the radar antenna is placed in contact with a carot-id artery model the radar is able to measure a signal proportional to the artery wall movements.

This paper presents a novel hybrid indoor localization solution that combines a wearable K-band trajectory-tracking Doppler radar with an ultra-wideband (UWB) positioning system. A K-band Doppler radar aided with a three-axis digital gyroscope is used to capture the Doppler frequency and the change in the heading direction, thus constantly tracking the trajectory by integrating speed into position change. In order to remove the error accumulated during the integration process, UWB positioning is adopted in a fixed region. Every time a subject walks into the region that is reliably monitored by the UWB positioning system, the location of the subject and the heading direction are calibrated by the UWB measurement result. Details of the tracking theory is presented. Experiments were carried out to demonstrate the advantage of the proposed Doppler-UWB system for short-range indoor localization.

This paper presents a high sensitive microfluidics flowmeter based on a complementary split-ring resonator (CSRR) sensor which can detect a tiny amount of 1.65 μL unknown fluid using permittivity estimation. The CSRR can detect the spatial distribution of the fluid to calculate the tangent flow rate. A multi-ring with tapped feeding is designed to improve the sensitivity and wide measurable dynamic range and to enhance the high resolution of position. Analysis of the sensor was calculated to estimate the resonance frequency. Microfluidics was fabricated using a glass substrate to achieve a high quality factor sensor. From the measured results, there is an average error of 6% using a single ring Rogers sensor. Moreover, the average error can be reduced to 3.35 % using the glass sensor.

In this paper, a new technique is introduced to enhance the sensitivity of microwave resonators. Double split ring resonators are implemented as the core of active resonators. It is illustrated that regenerative feedback could produce higher order intermodulation products at the output signal. The variations in sensing tone are multiplied, which indeed exhibit considerably higher sensitivities at 3rd, 5th, and 7th IM components compared to the main resonant frequency. The sensor is also integrated into wireless platform with ultra-wideband bowtie antennas. Common fluids such as Toluene, IPA, Methanol, and Water are tested in a fluidic channel and demonstrated that the sensitivity for intermodulation products are significantly increased. It is expected that such behavior reduces the limit of detection and enables more sensitive measurements.

For an effective plasma process control, the determination of the process parameters at multiple positions inside the plasma reactor is required. Utilizing the concept of the multipole resonance probe, different parameters of low-pressure plasmas can be derived based on a single broadband measurement of the complex reflection coefficient. In this paper, we present a prototype electronics for fast and accurate reflection measurements of multiple probes based on linear frequency ramps. Its performance has been analyzed by measurements in the frequency range from 0.1 GHz to 5.5 GHz in case of different microwave filters. The results are in very good agreement with those obtained with a commercial vector network analyzer, while the sweep time of 1 ms is significantly shorter. The applicability of the prototype electronics for plasma diagnostics over a wide range of plasma process parameters has been proven by measurements using a double inductively coupled plasma reactor.

In this work a novel fully passive chipless wireless cure monitoring sensor for fibre-reinforced plastics (FRP) structures is presented. The sensor is the first system, that enables locally wireless monitoring of the rising cross-linking level of the polymer molecules and the reaction temperature of epoxy resins during the exothermic curing reaction at particular critical locations inside of FRP structures. The temperature and permittivity of the reacting epoxy resin composition is determined by measuring and evaluating the change in resonance frequency for two substrate integrated waveguide (SIW) resonators. The obtained measurement results show an excellent accordance with the data provided by the widely used and established cure monitoring technique differential scanning colorimetry (DSC).

A method to increase the sensitivity for detection of thin dielectric materials with low thickness below 10µm is presented. By structuring a Polyethylene terephthalate (PET) substrate and introducing a floating electrode in a resonant Jerusalem cross unit cell, the sensing electric field can be confined in the thin material under test (MUT) yielding an increased sensitivity compared to strictly planar resonant structures. Analysis of the achievable sensitivity in terms of resonance frequency shift is performed for MUT thicknesses below 10µm at 0.5THz. Measurements demonstrate the detection of a dielectric layer with a relative permittivity of 2.4 and thickness of 3.3µm.

A novel wearable and flexible energy harvesting circuit for simultaneous DC power supply and RFID range extension is proposed. The proposed circuit is more efficient than conventional architectures because both the DC and harmonics generated by the rectifiers are utilized to serve two different functions. The DC power is used to drive DC loads and the harmonic is used to build a carrier emitter to increase the reading range of passive RFID tags. The 3D printing substrate is used to alleviate the limitations imposed by the substrate. Both the energy harvester and the passive tag are fabricated and characterized. The measured DC and the second harmonic, 928 MHz, output power from the proposed rectifier are 17.5 dBm and 1.43 dBm while a two-way talk radio is 9 cm away. The reading range of the custom tag is extended to 17 m with the help of the proposed energy harvester.

Simultaneous Wireless Information and Power Transfer (SWIPT) studies the transmission of wireless energy and data in a single RF signal. It becomes interesting when a single receiver chain is able to both convert the RF power to DC power, while at the same time converting the RF signal to BaseBand (BB). A practical method to receive the RF signal and convert the signal to BB while simultaneously harvesting power is proposed. This purpose is possible by utilizing a two-tone signal with a suitable Hybrid Rectifier-Receiver (HRR). The efficiency of the rectifier with different symbols can vary from 39% to 43% considering the power of the first tone as -11 dBm. Therefore, all symbols provide a descent DC output power. The proposed decoding is able to grasp the non-linearity of the diode in order to have a precise estimation of the symbols with different power levels.

This paper proposes and demonstrates a concurrent 2.45GHz/5.8GHz rectifier. The proposed concurrent dual-band rectifier drastically improves its RF-DC conversion efficiency with a harmonic signal control technique. The proposed rectifier em-ploys two key designs. A microstrip spurline notch filter realizes high RF-DC conversion efficiencies at the dual band. The quarter-wave length open stub of the 8.25 GHz at diode cathode effectively terminates the harmonic signal generated by mixing the input signals. The proposed configuration provides the high RF-DC conversion efficiency even when two-tone signals input the rectifier. The fabricated the dual-band rectifier achieves the RF-DC conversion efficiencies of 64.8 %, 62.2 %, and 67.9 % at 2.45 GHz, 5.8 GHz, and their two-tone input signals at 10-dBm input power, respectively.

This paper presents a novel wireless power and information transfer (WPIT) in a closed space utilizing frequency selected surfaces (FSSs). The framework of a greenhouse or a building can be considered as the FSSs. Therefore, the frequency of the power provided to the sensors can be confined inside the frame-work and a communication frequency to the sensor can be transmitted and received from the outside. The concept using a metal mesh box with a shelf is demonstrated. First, it is confirmed that the power transfer frequency can be confined inside the box by S-parameters from port 1 to each received port and the electric field standing wave in the box. Then, it is demonstrated that the power can be transferred to the Line-Of-Sight (LOS) and Non-Line-Of-Sight (NLOS) sensors in the metal mesh box and the sensing data can be received outside the box.

This paper introduces the concept of constant current power amplifier (PA) for magnetic resonance wireless power transmitters, where the current output of the PA remains almost constant when the load impedance varies. The solution enables the wireless power transfer system to simultaneously support multiple devices and naturally supply the power demanded by receivers without feedback control. In this paper, the design methodology of such PA will be discussed in detail followed by a design example.

This paper will present the design of position-independent inductive wireless power transfer (WPT) system for dynamic applications where power is required to be delivered to a moving object on a path, such as industrial sliders and mass movers. A key feature of the designed inductive WPT system is to inherently maintain a constant dc output voltage, dc output power and dc-to-dc efficiency of the overall system, regardless of the vehicle position. The system consists of an array of transmitting coils, where each coil is driven by a 6.78 MHz constant amplitude current generated from a load-independent Class EF inverter. The receiving coil is series tuned and is connected to a Class EF2 rectifier, numerically optimised to produce a DC output voltage which is also independent of the load. The systems is powered from 70V and GaN and SiC devices are used to implement the Class EF inverter and rectifier.

This articles describes a K/Ka-band active phased array antenna (PAA) component and mobile terminal technology development project to demonstrate dual-beam K-band Receive, switchable beam Ka-band transmit PAAs and miniaturized frequency converter technologies. The results support wideband satellite Comm. On-The-Move (COTM) requirements of future mobile vehicle construction. The prototype mechanically augmented phased array (MAPA) antenna terminal uses a combination of mechanical and electronic steering to provide full-hemispherical coverage with single phased array panels suitable for installation onto a variety of existing mobile platforms. The USAT MAPA terminal provides simultaneous (LHCP/RHCP) dual-beam K-band receive capabilities as well as a switchable (LHCP/RHCP) Ka-band transmit beam to significantly increase the data-rate capacity over a comparable mechanically gimbaled dish antenna. The USAT MAPA terminal can simultaneously receive from two sources and transmit to a third point with less than a 3dB axial ratio over the wide Field-of-View (FOV).

This paper analyzes the signal quality achievable with a novel system architecture for low-power small cell remote units with integrated millimeter-wave wireless backhaul. The data signal on the backhaul link uses the same 3GPP compliant signal as with the access link serving the users. In contrast to existing systems, the small cell remote unit (RU) only (RU) consists of a simple frequency conversion from backhaul to access frequencies based on the self-heterodyning mixing concept with suppressed local oscillator (LO) signal. Therefore, it omits the LO source and greatly reduces power consumption and hardware complexity. Its sufficient linearity and phase noise performance at 60GHz was proven with measurements of an LTE signal easily meeting the 3GPP ACLR and EVM requirements, even with varying LO suppression levels on the backhaul link. Moreover, the required frequency stability of the access signal is demonstrated even when using a very unstable LO source.

The full duplex channel, which describes the reflection interfer-ence signals in full duplex system, needs to be measured to achieve more precision SIC for full duplex system. Full duplex channel includes both strong leakage interference and weak re-flection interference signals, which requires very high dynamic range in channel measurement. In this paper, we designed a high dynamic channel sounding system for the full duplex channel measurement which can provide above 60dB measurement dy-namic range, we also performed outdoor full duplex channel measurement at 2.6GHz based on the proposed channel sounding system. The full duplex channel parameters distribution analysis was also performed based on the channel measurement results.

A technique for the spatial-spectral analysis of the cellular environment by performing a near real-time imaging of k-space is presented. The system uses a random spatial-spectral dispersion map from an optically-upconverted RF phased array receiver and tomographic reconstruction techniques to recover the cellular source scene. While spatial dispersion is inherent to phased array antennas, temporal dispersion is introduced by randomizing the fiber length for each up-converted antenna ele-ment, which contains the received RF signal as a sideband on an optical carrier. Each fiber is routed into a common fiber bundle where the filtered RF-sidebands are launched into free space, expand and overlap. The resulting complex superposition pro-duces an interference pattern unique to a given RF source loca-tion and frequency, which is used to recover the spatial direction and frequency of each source in the cellular environment. We present the theory of operation and experimental results of this approach.

This paper presents a quadrature self-injection-locked (SIL) radar to detect the displacement of a moving subject. Owing to the quadrature phase-switching architecture and corresponding digital signal processing techniques, this proposed system is capable of achieving excellent detection sensitivity and determining the target’s Doppler phase shift without being affected by nonlinear distortion caused by the SIL phenomenon. In the experiment, a metal plate is driven by a laptop-controlled linear stage, and a 2.4-GHz ISM-band prototype is placed 1.25 m away from the target to detect its motion. As a result, the measured error is less than 3 mm for the moving plate with a peak-to-peak displacement up to 5 cm.

In this paper a combined Ground Penetrating Radar (GPR) and Synthetic Aperture Radar (SAR) technique is introduced, which considers the soil surface refraction and the wave propagation in the ground. By using Fermat’s principle and the Sober operator, the SAR image of the GPR data is optimized, whereas the soil’s permittivity is estimated. The theoretical approach is discussed thoroughly and measurements that were carried out on a test sand box verify the proposed technique.

The linear sampling method (LSM) is an effective method to detect complicated structures in a short time. In this paper, we develop a novel kind of LSM by means of metamaterial (MTM) leaky wave antennas (LWAs) to conduct spectrally-encoded three-dimensional (3D) microwave tomography that can recon-struct a conductive target with coaxial multi-layer and various diameter cylinders. The unique frequency-space mapping fea-ture of MTM LWAs enables an efficient 3D microwave imaging with a larger field of view compared with conventional LSM approaches that usually operate at one single frequency. Vali-dated through both theoretical analysis and experimental re-sults, the proposed MTM imaging scheme allows us to recon-struct 3D shapes effectively with minimal prior knowledge of the target and computational resources. Furthermore, the meas-ured results verify the proposed imaging method by successfully detecting the unknown targets with different shapes and loca-tions for the MTM LWAs operating at 1.8-3 GHz.

Proximal-Field Radiation Sensors (PFRS) are introduced as a new set of tools to enable extraction of far-field radiation properties of integrated antennas from the surface waves inside their dielectric substrates. These sensors allow self-characterization, self-calibration, and self-monitoring of the ra-diation performance for both printed circuit board (PCB) anten-nas and integrated circuit (IC) antennas without any need to additional test equipment. A PCB prototype consisting of two transmitting patch antennas and four integrated PFRS antennas is fabricated and tested to verify the concept and demonstrate the implemented sensors’ capabilities to capture the radiation prop-erties such as gain pattern, radiated polarization, and the steering angle of the antenna array as a few examples of radiation sensors applications.

We propose a disposable, miniaturized, moveable, fully integrated 3D inkjet-printed wireless sensor nodes for large area environmental monitoring applications. We show the wireless sensing of temperature, humidity and H2S levels which are important for two critical environmental conditions namely forest fires and industrial gas leaks. The temperature sensor has TCR of -0.018/°, the highest of any inkjet-printed sensor and the H2S sensor can detect as low as 3 ppm of gas. These sensors and an antenna have been realized on the walls of a 3D-printed cubic package which encloses the microelectronics developed on a 3D-printed circuit board. Hence, 3D printing and inkjet printing have been uniquely combined in order to realize a unique low-cost, fully integrated wireless sensor node. Field tests show that these sensor nodes can wirelessly communicate up to a distance of over 100m.

The rapid and accurate assessment of burn injuries is a very challenging task in burn surgery. To illustrate the potential of millimeter-wave systems for burn diagnosis, the current paper at first shows a coaxial probe based ex-vivo measurement of the effective relative permittivity of skin depending on the degree of burn and also in-vivo measurements of the relative permittivity change caused by small skin irritation (i.e., increased or decreased blood perfusion, edema formation) in the frequency range 0.1 to 50 GHz. Based on the presented relation between skin condition, frequency, permittivity and loss, a MIMO-SAR imaging system operating at 75 GHz is introduced that facilitates a near real-time skin diagnosis. A skin model based on ex-vivo porcine skin is utilized to image the stepwise increased degree of a burn wound. In addition, for the first time in-vivo imaging results of normal and irritated human skin are presented.

In this paper, radiometry measurements of human tissue layer phantom temperature are presented. A skin-fat-muscle phantom allows independent heating/cooling of the lowest layer. A narrowband probe is designed specifically for that tissue stack-up and a sensitive radiometer is used for measuring total radiometric power in the 1.4-GHz quiet band. The knowledge of the volume power loss density from the probe, obtained from full-wave simulations, is used to determine the tissue weighting functions, which in turn allows for estimating black-body power radiated from a specific buried layer. Measured data using a Dicke radiometer shows that the radiometer tracks the internal tissue temperature.

Microwave holography is a direct inversion algorithm that shows promise for use in real-time near-field tissue imaging. However, the methodology depends on the linearization of the scattering problem which, in reality, is nonlinear. Therefore, the choice of the linearization method significantly impacts the reconstruction output of holography. Two linearization strategies, the Born and the Rytov approximations, are explored. To analyze their fidelity, the approximations are applied to tissue-imaging problem. Results suggest that the Rytov approximation is advantageous in tissue imaging.

This work presents the feasibility demonstration of an automatic RF leakage cancelling circuit for a simultaneous transmit and receive (STAR) system for magnetic resonance imaging (MRI) applications. The automatic system with wireless control enables a radiofrequency (RF) coil to achieve greater than 40 dB decoupling between transmit and receive ports with 900 ms resolution. The system stability and noise contribution to MR images were evaluated. To demonstrate feasibility of this approach, a NMR MR image was acquired by transmitting an RF excitation pulse and acquiring an MR receive signal simultaneously on a 4-tesla (T) MRI scanner.

This paper presents a study of a volume excitation of a human-sized MRI bore at 10.5\,T using a circular patch, an interdigitated capacitor probe (ICP) array, and a combination of the two. Compared to an experimentally verified single patch probe excitation, the ICP array allows for |B1+| shimming by modifying the magnitude and phase of the elements to fill the field void left near the edges of an uniform phantom. Simulations using full-wave FDTD show an increase in field coverage inside of the uniform phantom which can further be improved by the addition of a simple, passive slow-wave helical boundary structure.

Here we describe a 395 GHz pulsed electron paramagnetic reso-nance (EPR) setup, and initial results of relaxation measurements and cw EPR at these frequencies in samples used for liquid- and solid-state nuclear magnetic resonance enhanced by dynamic nuclear polarization (DNP). Depending on the amount of spin–orbit coupling, the spin lattice relaxation becomes significantly faster at higher fields and frequencies, which has consequences for some DNP applications at high fields and frequencies. We will discuss the requirements for (sub)millimeter-wave sources and components for DNP and pulsed EPR at even higher frequencies and fields, as even higher magnetic fields will become available in the near future.

This paper presents a fully-integrated D-band bistatic frequency-modulated continuous-wave radar transceiver (TRX) chip based on 130nm SiGe BiCMOS technology. The TRX chip consists of an active IQ modulator and an IQ downconversion mixer. It is based on a x6 frequency multiplier chain. The entire chip is optimized for wideband operation. The TRX chip and the circuit break-outs are characterized on wafer. The TRX chip demonstrates state-of-the art performance with a peak output power of 11 dBm and a 3-dB bandwidth of 30 GHz. The on-chip receiver provides a measured conversion gain of around 15 dB and a simulated minimum noise figure of 8 dB, with a 1-dB input compression point of -7.5 dBm. The IQ receiver shows a good balanced behavior with an average amplitude imbalance of 0.5 dB and a phase variation from 93 to 98 throughout the 3-dB bandwidth. The chip consumes total DC power of 825 mW.

This paper presents a 60GHz monostatic transceiver system for FMCW radar applications. The IC occupies a very compact area of 1.42x0.72mm² and is fabricated in a 250/340GHz fT/fmax of 0.13µm SiGe BiCMOS technology with a total current consump-tion of 190mA from a single supply of 3.3V. The fully differential transceiver employs an I/Q receiver with 17dB conversion gain and -20dBm input 1dB compression point and a transmitter with 8.2dBm output power with a 3-bit push-push voltage-controlled oscillator integrated to a divide-by-32 block for external PLL operations. The single antenna output functionality is guaranteed by the tunable high isolation coupler integrated to TX/RX chan-nels. Additionally, two power detectors monitoring transmitted and reflected powers on TX channel through a branch-line-coupler are designed as built-in-self-test blocks. The successful real-time measurement results indicate that the proposed monostatic transceiver system is able to detect obstacles above 90m and is well suited for 60GHz radar applications.

This paper presents a digital pre-distortion scheme to reduce carrier-leakage in wideband FMCW radars that use a circulator to provide isolation between the transmitter and receiver. The proposed digital pre-distortion technique first power combines the leakage signal with a second pre-distorting signal prior to entering the radar receiver. The Phase & amplitude of this pre-distorting signal are adjusted for partitions of the FMCW chirp to provide cancellation. Transitions between sections are pulse shaped to eliminate broadband frequency content.

This paper presents a Ku-band FMCW radar transceiver IC realized in 0.13 μm CMOS processes. In the radar receiver, a sensitivity time control using a DC offset cancellation feedback loop is employed, which preserves the receiver’s SNR not depending on the distance. The radar receiver achieves the full chain gain of 82 dB, P1dB of -2.0 dBm at the minimum gain, and noise figure of 7.9 dB with 106 dB dynamic range. The measured result of the radar transmitter reveals 9 dBm output power. The radar transceiver consumes 115 mA from a 1.2-V power supply. With the aid of an external PLL, the Ku-band FMCW radar module is implemented and verified radar func-tion by measuring the distance of various objects.

A linearity improvement method of a fast-chirp signal for a PLL by using a frequency detector and a division ratio modification is proposed. A fast-chirp signal generated by the PLL is distorted by its transient characteristic. The proposed method measures a frequency difference between the output and an ideal signal, and it modifies the division ratio of the PLL from the measurement result. An iteration of the modification of the division ratio in the proposed method enables higher linearity improvement. Experi-mental results show that the maximum frequency error decreases by 90.3% after 3 times of iteration compared to that without the proposed method. Measured chirp linearity L, which is defined as division of the maximum frequency error by a modulation speed is 0.93μs.

This paper presents a smart communication system for simultaneous data reception and direction of arrival estimation for firefighters, rescuers, and other emergency personnel. The system consists of a passive six-port microwave interferometer which transforms the challenge of an accurate phase measurement for direction estimation to a relative power measurement. This can be easily realized by the readout of the received signal strength indicator of low-cost commercial off-the shelf transceivers which are simultaneously used for communication. Due to the differential IQ structure the robustness of the system is enhanced, even for severe disturbance and interference, where it still can provide a relative angle of emergency team members to each other.

The theoretical and experimental evaluation of using biomimetic antenna arrays (BMAAs) in an angle sensing radar system is presented. This ultra compact antenna system can enhance the angle estimation accuracy for radar systems which allow only small antenna separations due to the available space. A quality criterion will be given to indicate which BMAA parameters are necessary to achieve precise angle estimation accuracy. Radar measurements show a reduction in the RMS angle estimation error by a factor of 2 compared to conventional antennas of same size.

In this paper the authors report the first 5G-compatible implementation of a long-range, energy autonomous, mm-wave RFID sensor for IoT applications. The system topology is first described, before the design and performance characterization of its constituting components, including an inkjet-printed carbon-nanotube(CNT)-based ammonia sensor, are presented. Then, the entire printed mm-wave backscatter-modulation device is tested, demonstrating a monostatic radar cross-section of -29 dBsm, with only a 10 dB variation within the -50 to 50 interrogation angular range. The wireless ammonia sensing capabilities of the system are then demonstrated, before its detection at an ultra-long-range of 80m is reported.

This paper presents an approach for the design of chipless RFID tags by using standard alphabets. To illustrate this approach, the paper considers the alphabet letters (a, b and c) that are realized using copper etching on 0.5mm thick Taconic TLX-8, with a relative permittivity of 2.55 and loss tangent of 0.0019. As expected, simulation results demonstrate that the exploitation of resonant frequencies visible in the backscatter signal can be used for purpose of identification. Simulations results are confirmed by experimental measurement and validate the proposed coding approach

This paper presents a novel approach for the implementation of chipless RFID systems, suitable for authentication and security applications. The tags consist of a set of identical resonators etched on a dielectric layer. The resonators are located at equidistant positions in such a way that the presence or absence of resonators corresponds to the ‘1’ or ‘0’ logic states, respectively. The reader is a coplanar waveguide (CPW) transmission line fed by a harmonic signal tuned to the frequency of the resonant elements. In a reading operation, the tag must be transversally displaced over the CPW, so that the resonant elements modulate the amplitude of the feeding signal. This sequential bit reading alleviates the spectral bandwidth limitations since the resonators are all identical. The design of 10-bit encoders based on this approach, and implemented by means of S-shaped split ring resonators, is reported. The area of the encoders is 1.35 cm2.

Depending on magnetic fields caused by phase differences between the adjacent transmission lines for high precision UHF near-field sectional localization systems, a fourport selective differential feeding network is presented. The proposed four-port feeding network consisting of four quadrature hybrid couplers and 90 degree phase delay lines can selectively generate a differential phased current on a particular transmission line. The maximum insertion loss within the authorized UHF RFID frequency band (902–928MHz) has a 7.1dB loss including the theoretical 6dB power distribution loss, and the maximum amplitude imbalances and phase error have less than +-0.5dB and +-10 degree, respectively. By switching the input ports, the sectional identification with regard to tag positions on the 10 mm height away from parallel transmission lines can be achieved. The proposed system using a four-port selective differential feeding network makes it possible to utilize a near-field position detection application such as a smart shelf.

A compact passive two-bit metamaterial based phase-modulated chipless RFID tag with a temperature sensor is presented. The chipless RFID tag with temperature sensor operates at 2.4GHz. The chipless RFID tag consists of the following, 1) composite right/left handed(CRLH) based antenna operating at 2.4GHz, 2) CRLH delay lines operating in the left-handed (LH) region at 2.4GHz, 3) digital phase modulating sections realized using the distributed approach, and 4) thermistor for the sensing of temperature. The phase of the backscattered signal over a period of time is used for identifying a particular tag and sense the temperature. QPSK is implemented using the four phase modulating sections having unique input reflection coefficients corresponding to the four symbols. Analog phase modulation is used for the temperature sensing. The dimension of the chipless tag with two phase modulating sections at the operating frequency of 2.4GHz is 0.86λ0×0.16λ0×0.00648λ0 with a footprint reduction of 28% is achieved.

A state-of-the-art fully inkjet-printed tunable frequency selective surface on cellulose paper is presented, which uses a Miura origami structure to linearly change on-demand the inter-element distance and the effective length of the resonant dipole elements, resulting in an observable shift in the operational frequency of the structure. The dipole elements are placed on the foldlines along with special ``bridge-like" structures to realize truly flexible structures over sharp bends. A novel multilayer-FSS approach is also presented which results in three times increase in the percentage bandwidth as compared to the single-layer design. The design also features an excellent angle of incidence rejection

The first-of-its-kind origami antenna ``tree" model was presented, enabling the integration of multiple 3D antennas with a minimal interference and an on-demand reconfigurability of frequency, polarization and radiation pattern to optimize performance in changing environments. Liquid metal alloy(LMA) was used to switch between antennas and to enable flexible implementations. An origami structure, the zipper tube, coupled with Voronoi topology implementations was used as the scaffolding structure facilitating the mechanical tuning of the radiation pattern while minimizing storage requirements. The ``tree" was fabricated by 3D printing, enabling on-demand fast-prototyping and low-cost manufacturing. A proof-of-concept two-antennas ``tree" (zigzag/helical antenna) was presented, featuring a dual-band (3GHz/5GHz) operability and different polarizations (linear/circular) along with varying radiation patterns with "tree" compression. The ``tree" can be applied to various dynamically changing scenaria such as wireless communications, collapsible/portable radars, satellite communications, which can realize numerous other reconfigurable RF components, such as filters, reflectors and shielding structures.

While 3D printing has enabled the rapid prototyping of numer-ous 3D structures, only very few designs have exploited this tech-nology to create structures that are difficult or impossible to manufacture in any other way. In this paper, a novel surface modification technique is combined with high-resolution Stereo-lithography 3D printing to enable arbitrary 3D antenna designs that have never been demonstrated before including a Voronoi tessellation for light weight, low volume, and aerodynamic prop-erties and 3D fractal geometries featuring similar physical ad-vantages. Both antenna topologies utilize a novel metallization technique, electroless copper plating, to overcome the highly lossy properties of common 3D printed dielectric materials.

This paper presents a helical resonator bandpass filter produced using a stereolighography (SLA) based 3-D printing technique. The filter is formed of four coupled helical resonators, and for each resonator the helix is fixed at both ends so that the resonator is less prone to vibration. The helix is designed to have variable width and this yields enhanced performance in terms of a higher unloaded quality factor and a spurious resonance at higher frequencies. Such a helix is ideally suited to 3-D printing which allows easy production of complex structures. The whole filter is printed from a resin, then plated with metal, and tested. The measured result has a good agreement with simulations.

A new class of hemispherical resonators featuring a high unloaded quality factor (Qu) and a compact geometrical configuration is proposed for the first time for 3-D printed bandpass filter (BPF) applications. The hemispherical resonator exhibits a volume only half that of a spherical one at a same dominant-mode resonant frequency, without losing its intrinsic high-Qu characteristic. Second-order BPFs based on such resonators are designed at X and Ka bands. The Ka-band BPF is manufactured with a high-temperature-resistant ceramic-filled resin using a fast and low-cost stereolithography-based 3-D printing technique for validation purpose. The filter's surface metallization is achieved by employing electroless copper/silver plating, which contributes to an improved fabrication accuracy in thickness and uniformity of the conductive layer. The RF-measured results demonstrate the Ka-band filter an insertion loss of 0.56−0.7 dB at 31.95−32.13 GHz, a passband return loss of better than 17 dB, and a small frequency shift of 0.04%.

A Ku Band (15~18 GHz) 8-Element (4 Transmitters/4 Receivers) fully differential phased array transceiver is designed and fabricated using a 180nm CMOS process. The proposed phased array integrated with T/R switches and SPI controller is based on an all-RF structure. TX and RX channels are placed side-by-side to improve integration density and isolation. Each channel consists of a 5-bit phase shifter and a 4-bit attenuator. The measured maximum gain is 21 dB for a TX channel and 10.8 dB for a RX channel. The minimum noise figure of RX with T/R switch is 9.9 dB. The input referred P1dB of RX is -14.5 dBm at 16GHz, while the output referred P1dB of transmitter is 10 dBm at 16 GHz. Additionally, the RMS phase error of phase shifter is less than 4o, and the RMS amplitude error of attenuator is less than 3.2 dB。The chip occupies 4.5*5mm2 area including pads.

This paper presents a 64 GHz transmit/receive communication link between two 32-element SiGe-based phased arrays. The antenna element is a series-fed patch array, which provides directivity in the elevation plane. The array can be scanned in the azimuth using a 5-bit phase shifter. The transmit array results in an EIRP of 42 dBm, while the receive array provides an electronic gain of 33 dB and a system NF < 8 dB including the T/R switch and antenna losses. Data rates of 1 Gbps using 16-QAM and 2 Gbps using QPSK are demonstrated at 300 m. The system also results in > 4 Gbps data rate at 100 meters, and 500 Mbps data rate at 800 meters.

This paper presents an 8-channel bidirectional 60 GHz beamformer in a SiGe:C 130 nm BiCMOS technology, with fT / fmax = 250 / 340 GHz. The beamformer consists of RF switches, LNAs, PAs, vector modulators, passive dividers / combiners and an integrated SPI controller. On wafer measurements results show that the beamformer has an OP1dB of 0 dBm in Tx mode and an IP1dB of -26 dBm in Rx mode, consuming only 550 mW in both operation modes and occupying a silicon area of 27 square millimeters.

Digital beamforming/MIMO arrays provide increased capacity, flexibility and reconfigurability but the absence of spatial filtering of jammers prior to the ADC restricts RX linearity. In this work, a reconfigurable, scalable parallel spatio-spectral notch filtering (PSNF) array is presented that incorporates orthogonal Walsh function sequence mixing with Npath passive mixers. Sequence mixing and impedance translation of passive mixers result in concurrent notching at each element’s RF input for two independent frequencies/angles-of-incidence defined by the sequence driving the mixers. A 0.3 GHz-1.4 GHz four-element array prototype implemented in 65-nm CMOS achieves > 15-dB notch filtering at RF input for two blockers while causing < 3-dB NF degradation. The array achieves ∼28- dBm RX OIP3 (with PSNF enabled) and wireless measurements demonstrate spatial rejection of in-band blockers.

A 0.96-to-5.1GHz 4-element antenna array is described. The beamformer is designed in 0.13μm CMOS using a delay-and-sum (DAS) architecture enhanced with a spatially analog IIR filter for sidelobe reduction. The DAS portion is based on a novel delay element that provides 82ps delay range and consumes 6.15mW of power. The beamformer circuit is measured to achieve sidelobe levels of -22dBc, which is a 10dB improvement over prior art.

A Ku-band build-in-self-test (BIST) chip in CMOS is presented for RF beamforming arrays in 5G mobile communication systems. Since the beamforming array in 5G systems has hundreds of antenna elements, the BIST circuits must be incorporated in the RF chains to be able to accurately detect and control the phase and amplitude of the signal such that the required beam shape and direction can be precisely generated. The BIST based on the phasor-sum detection method is designed in 90 nm CMOS technology at Ku-band. The measurement results show that the relative phase detection error is less than 5.9 degrees, compared with the data directly from the vector network analyzer.

Electro-optic (EO) field probes can be used very effectively for simultaneous near-field and far-field characterization of radiating apertures. Due to their very small footprint and absence of any metallic parts at the signal pickup area, EO probes provide a non-invasive method for ultra-wideband measurement of aper-ture-level fields in RF circuits and antennas with very high spatial resolution. In this paper, we describe the use of EO field probes with a CW laser source to characterize a vertically integrated X-band active phased array tile and verify the measured results with simulation data and anechoic chamber measurements.

This paper presents a dielectric waveguide based multi-mode sub-THz interconnect channel for high data-rate high bandwidth-density planar chip-to-chip communications. By using a proposed new transition of microstrip line to dielectric waveguide, the interconnect channel achieves low insertion loss and wide bandwidth on two orthogonal modes Ey11 and Ex11. To the authors’ knowledge, this is the first demonstration of a multi-mode sub-THz interconnect channel. The measured minimum insertion losses for mode Ey11 and mode Ex11 are 8.0 dB with 21.3 GHz 3-dB bandwidth and 9.0 dB with 24.0 GHz 3-dB bandwidth, respectively.

This paper presents two types of wideband transitions from a flip-chip interconnect to external v-band rectangular waveguides and surface-mount coaxial connectors, based on LTCC technology. The flip-chip interconnect is directly connected to a multi-level stacked via allowing compact routing of RF signals for a highly dense phased array system-in-package. The signal is guided from striplines into the waveguides using a T-shape launcher and impedance matching is performed by several means including implementing a stub and tapering a near-quarter wavelength embedded waveguide. In the other design, mm-wave signals are directed from a stripline to a surface mount 1.85 mm v-type connector to provide a compact solution for multiple input/output transceivers. Both types of transitions are fabricated and initial measurement results are presented. Compactness and low loss (0.5 dB) performance along with over 20 % bandwidth from 55 to 67 GHz make the transitions suitable for 60 GHz WiGig applications.

This work explores the integration of 3D and inkjet printing manufacturing processes with millimeter-wave (mm-wave) wireless packaging technology. Stereolithography-based (SLA) 3D printing methods are discussed for two classes of materials: polymeric and ceramic-loaded dielectrics. 3D-printed materials are characterized for performance within the E-band wireless regime (55–95 GHz), extracting relative permittivity and loss tangent. Thermal cycling tests are performed in order to evaluate the thermal stress characteristics of the printed dielectrics structures. Die encapsulation with SLA printing technology is presented as an alternative to the standard molding and stamping technology. Inkjet printing is used to demonstrate the fabrication of metallic structures directly onto 3D-printed packages, highlighting potential applications of on-package antenna arrays, lenses, and metamaterial surfaces. Finally, inkjet-printed mm-wave transmission lines are realized on 3D-printed ramp structures, demonstrating efficient 3D interconnects with ramp slopes up to 65° for through-mold-via (TMV) solutions.

Q-Band receiver and transmitter beamformer channels using 250 nm InP HBTs and 130 nm Si CMOS have been fabricated in a three-dimensional wafer-stacking platform. Room-temperature face-to-face wafer bonding is accomplished using a hybrid bonding technique (Direct Bond Interconnect®) of 2.5 micron wide, 5 micron pitch copper inlaid in silicon dioxide to form electrically active vertical interconnects. 3-bit amplitude and 4-bit phase modulation receive and transmit channels are characterized. At 40 GHz, the receiver and transmitter chains have more than 25 dB gain, with 6 dB variable gain tuning, and less than 5° RMS phase error. The transmitter saturated output power is 20.3 dBm. To the authors’ knowledge, this is the first demonstration of wafer-scale three-dimensional integration of Si and InP MMICs towards RF beamforming applications.

We present an ultra-compact channelized radiometer back-end module implemented in an LTCC process, featuring an 8-channel, wide bandwidth multiplexer. The multiplexer has 8-channels covering 4.3 GHz to 11.1 GHz (104% overall fractional bandwidth) with 2.1% to 8.4% fractional bandwidth channels, designed using a hybrid channel-dropping approach. The multi-layer module integrates the stripline multiplexer with microstrip diode detectors, SMT amplifiers and other components in a 30.5 mm by 61.0 mm footprint. Design, simulation, and fabrication of the multiplexer and its application to small and low-power radiometers is discussed, along with results of the flight module scheduled for launch in a 2017 CubeSat mission.

A novel receiver architecture based on frequency translation is proposed. The receiver treats a monolithically integrated time-varying transmission line (TVTL) as a capacitive mixer with minimum insertion loss and noise penalty, places it in the first stage before a fixed, narrow bandpass filter. By varying the LO/carrier frequency to the TVTL mixer, the complete received frequency band is shifted so that the desired band can be selected with a fixed bandpass filter, without suffering SNR degradation that usually appears in a conventional heterodyne receiver with mixer at its first stage. Measured results of both the TVTL MMIC and the testbed of the frequency translational receiver validate the proposed concept and confirm its potential for applications in software defined radios.

A 0.7-1GHz tunable FEM is presented for FDD and IBFD that uses an electrical-balance duplexer (EBD) and tunable SAW res-onators, demonstrating for the first time that these techniques are compatible and independently tunable. The EBD is integrated with an LNA in 0.18µm SOI CMOS and operates with any

Modern communication systems are becoming increasingly intricate as the technology that governs their development progresses. At the same time, an increasing number of users puts a greater burden on the performance of these systems. Modern communication systems are required to process transmitted and received signals simultaneously over a broad bandwidth. SSDL, which stands for Sequentially-Switched Delay Lines, provides a solution to this problem. The SSDL concept is a time-switching strategy, which uses a set of transmission lines and switches to route transmitted and received signals to their respective ports simultaneously over a wide bandwidth. Experimental results show that the SSDL system has the capability to provide full duplex communication over a broad bandwidth.

A dual-mode receiver architecture with tens-MHz channel bandwidth at microwave mode and GHz channel bandwidth at millimeter-wave mode is demonstrated in this work with a tunable active filter for RF channel selection at microwave mode using 0.18 um SiGe BiCMOS technology. A dual conversion is employed to accommodate the wide-channel-bandwidth 60-GHz mode at the first conversion stage and the high-level-modulation 5-GHz mode is merged to the second conversion stage through sharing the 5-GHz switchable Gilbert IQ mixers with the 60-GHz mode. A tunable RF active filter is inserted between the 5-GHz LNA and the second stage mixer to serve as RF channel selection at the 5-GHz mode with the ability of relaxing the stringent linearity requirement imposed by high-level-modulation scheme.10 dB gain with a 2-GHz channel bandwidth at the 60-GHz mode and 23 dB gain with a 20 MHz channel bandwidth at 5-GHz mode are demonstrated.

This paper presents a low-power RF transmitter with harmonic injection locking and capacitively-coupling frequency multiplication techniques. To save power, the design operates at a low frequency except for the RF Class-E power amplifier. The chip, which was fabricated using 0.18 um CMOS technology, has an area of 0.49 mm x 0.93 mm. The proposed model can achieve a maximum transmission power of -21.3 dBm, data rate of 2 Mbps, and energy efficiency of 0.071 nJ/bit while consuming 145 uW.