This study examines K-band rectangular waveguide terminations with three-dimensional (3D)-printed loads, and proposes an Asymmetrical Tapered Wedge topology. This geometry shows a good tradeoff between microwave performance and 3D-printing issues (printing directions and support material requirements), thus improving noticeably the reproducibility of the devices. The effect of the density of the 3D-printed load on the reflection parameter of the termination was investigated. Even for a low density, reflection level remained below −27.5 dB between 18 and 26.5 GHz. Reproducibility was demonstrated by the characterization of six loads that were 3D printed under the same conditions. Measurements demonstrate that a maximum reflection parameter level of −33.5 dB can be ensured over the whole frequency band without any post-machining of the 3D-printed devices.

This paper presents the characterization and modeling process of MASMOS structures by means of a classical compact three-port electrical non-linear model approach. From DC and S-parameters measurements, a large signal model (LSM) has been developed for two different MASMOS structures. The proposed LSM and associated modeling approach have been validated through load pull measurements with different harmonic load conditions. Then, generic multi-tone measurements have been carried out making use of an innovative test bench to quantify linearity performances of MASMOS structures. The model is used in a power amplifiers design flow for LTE applications and is expected to allow a significant reduction of simulation time, compared with technological-oriented model as BSIM3.

An optically transparent and electrically small frequency modulation (FM) radio receiving antenna has been designed and fabricated from a mesh silver layer printed onto a glass substrate. The studied FM antenna consists of a transparent meandering monopole associated with a micrometric size MEtal Semiconductor Field Effect transistor. An optical transparency of 87% and a sheet resistance lower than 0.22 Ω/sq are obtained. The received signal strength indicator and the signal-to-noise ratio are both measured and compared with those of a commercial monopole antenna (a quarter-wave wire antenna). The transparent FM antenna exhibits similar radiofrequency performance with, in addition, a low visual impact.

A novel topology of high-gain millimeter-wave antenna compatible with substrate integration is presented. The antenna is composed of a planar discrete lens laid on top of a core dielectric, while the planar focal source is assembled on the bottom side. The antenna can be fabricated as a single, robust and compact module using standard low-cost PCB technologies, and is compatible with IC integration such as a transceiver circuit for fully integrated millimeter-wave front-end modules. The proposed architecture is studied with two compact V-band antennas (32 mm × 32 mm × 13.2 mm). The main design rules are demonstrated for unit cells, focal source, and planar lens at V-band. Promising performances in terms of gain (17.6 and 20.4 dBi), aperture efficiency (14 and 26%), and fractional 3-dB gain bandwidth (17 and 18%) are obtained experimentally for the two considered compact antennas.

This paper presents performances achieved with InAlGaN/GaN HEMTs with 0.15 µm gate length on SiC substrate. Technology Computer Aided Design simulations were used to optimize the heterostructure. Special attention was paid to the design of the buffer structure. I-V measurements with DC and pulsed bias voltages were performed. CW measurements at millimeter waves were also carried out and are detailed in the following sections. The technology, optimized for power applications up to 45 GHz, demonstrates a current gain cut-off frequency FT of 70 GHz and a maximum available gain cut-off frequency FMAG of 140 GHz. CW Load-pull power measurements at 30 GHz enable to achieve a maximum PAE of 41% associated with an output power density of 3.5 W/mm when biased at VDS = 20 V. These devices, with an improved buffer structure show, reduced recovery time in pulsed operating conditions. These improved characteristics should have a positive impact for pulsed or modulated signal applications.

This work presents the design of two compact multi-standard low-noise amplifier (LNA) in a 28 nm low-power bulk CMOS process. The transistor parameters were optimized by the gm/ID method taking into account the parasitics and the behavior of highly scaled transistors. To cover the industrial science medical (ISM)-bands around 2.4 and 5.8 GHz, the WLAN band as well as the Ku band a bandwidth enhancement is required. Two versions of LNAs, one with vertical inductors and one with active inductors, are implemented and verified by measurements. The noise figure (NF) exhibits 4.2 dB for the LNA with active inductors and 3.5 dB for the LNA with vertical inductors. The voltage gain reaches 12.8 and 13.4 dB, respectively, with a 3 dB-bandwidth of 20 GHz. Both input referred 1-dB-compression points are higher than −12 dBm making the chips attractive for communication standards with high linearity requirements. The chips consume 53 mW DC power and the LNA with active inductors occupies a core area of only 0.0018 mm2, whereas the version with vertical inductors requires 0.021 mm2.

This paper presents a broadband hybrid slot-dielectric resonator antenna for radiofrequency (RF) energy-harvesting application. The antenna geometry consists of a simple pentagon-shaped dielectric resonator antenna (PDRA) excited by a microstrip feed underlying rectangular slot with narrow notch. It is investigated that the bandwidth of the proposed PDRA is improved significantly owing to electromagnetic coupling between feeding slot and the dielectric resonator. The measured results demonstrate that the proposed PDRA achieves an impedance bandwidth of 110.8%, covering the frequency range from 0.86 to 3 GHz in addition of stable radiation pattern with peak gain of 6.8 dBi and more than 90% radiation efficiency throughout the band, showing its suitability for RF energy harvesting application. For this to be feasible, the developed antenna is matched with the rectifier at two public telecommunication bands of GSM-900 and GSM-1800 using a compact dual-band hybrid matching network. The measured result demonstrates that the proposed dual-band rectenna system provides the peak efficiency of 63 and 59% for a load impedance of 4.7 kΩ at 0.9 and 1.8 GHz, respectively.

Metamaterial-based energy harvesting structures operating at GSM 900 and GSM 1800 frequency bands have been proposed. The basic structure is composed of four nested U-shaped elements on the front and back side of the dielectric substrate, with a 180° relationship between the front and back resonators. As energy harvesting capability is directly related to the quality of absorption, with the aim being perfect absorption, there is an air gap to allow tuning of the resonance frequency, and copper plate follows the air gap to facilitate the perfect absorption of electromagnetic waves, which is verified by means of simulation and experimental tests. A set of simulations and experimental study were further carried out to demonstrate incident and polarization angle dependency, the effects of Schottky diodes, and the optimal orientation of the U-shapes. Spectrum analysis and DC voltage measurements across the HSMS 2860 Schottky diode are also presented to test the energy harvesting capability: the spectrum analyzer shows a 40 dBm difference, while 81.7 mV maximum DC voltage is observed at 900 MHz. The simulation and experimental study results, while displaying several differences, do suggest that the proposed design can be used for running low-energy consumption devices such as sensors and switches.

This paper presents a wideband, low-cost, high-performance, and continuous phase shifter for millimeter-wave (mm-wave) phased array systems. Its operational principle is based on modifying the propagation mode of a grounded coplanar waveguide (GCPW) line by placing a high dielectric constant slab over the GCPW line. The propagation constant and hence the phase shift is varied by changing the air gap height between the GCPW line and the dielectric slab. As a proof of concept, a piezoelectric transducer is used to precisely control this air gap height. A printed circuit board-based phase shifter prototype has been designed, fabricated, and tested at two different frequency bands (19–21 and 28.5–30.5 GHz), which are the downlink and uplink bands, respectively, of the Ka-band two-way satellite communication system. A continuous and almost linear phase–voltage characteristic has been achieved experimentally with average phase shift variations 170° and 260° over the two bands, respectively. The footprint of the proposed phase shifter is 2.1 mm×3 mm, which is quite small and suitable for low-profile mm-wave applications. The average insertion losses over the two bands are <0.53 and 2.35 dB with very low variations±0.22 and ±0.35 dB, respectively.

A passive evanescent mode half-mode substrate integrated waveguide (HMSIW) resonator loaded with a complementary split ring resonator (CSRR) is designed and fabricated for humidity sensing applications. The use of the CSRR which is etched on the top plane of the HMSIW can significantly reduce the size of the device. Without any sensing material, the sensor which has a compact size of 0.17λg × 0.17λg can provide high humidity sensitivity up to 5.82 MHz/%relative humidity (RH) at high RH region (>84.3%). The results indicate that the proposed structure is a promising candidate for radio and microwave humidity sensing applications.

In this paper, a dual-wideband bandpass filter (BPF) with independently controllable center frequencies (CFs) and wide stopband suppression is presented using a new quintuple-mode resonator (QMR). By applying the classical odd-/even-mode analysis method, the resonant characteristics of the new QMR have been analyzed. It shows that five modes can be excited, and two of them can be employed to form the lower passband, while the other three modes contribute to the higher passband. For verification, a dual-wideband BPF using the new QMR is designed, fabricated, and tested. Experimental results show that the CFs of the dual-wideband BPF centered at 2.96 GHz and 5.695 GHz with 3 dB fractional bandwidths of 27.7 and 23.4%, respectively. In addition, 20-dB suppression in upper-stopband ranges from 2.23 to 4.04f0, where f0 is the center frequency of the first passband. The measurement results are in good agreement with the prediction results.

An impulse response method is carried out to analyze waveguide's information capacity within a coherent communication system. Such capability is typically estimated according to group delay variations (seconds/bandwidth/distance) after carrier-modulated data undergoes a dispersive medium. However, traditional group delay methods often ignore non-linear effects by assuming input data stream only occupies narrow bandwidth such that a propagation constant can be linearized centered at the carrier frequency. Such a constraint can be lifted with a proposed baseband equivalent impulse response method by using frequency domain convolution and multiplication. Once the impulse response in frequency domain is secured, its time domain counterpart can be calculated based on inverse Fourier transformation. Such analysis can fully reveal data pulse's broadening and gauge its inter-symbol interference by simply convolving input data with extracted impulse response, not limited to specific frequency range or type of waveguide.

Jamming of synthetic aperture radar (SAR) is more difficult than the conventional radars because of its high processing gain. The defocusing of fake or virtual scatterers is the main problem that any jamming technique needs to tackle. An algorithm based on fractional Fourier transform is proposed for the efficient jamming of SAR. The results show that the performance of proposed algorithm is better than conventional Range Doppler Algorithm.

This paper presents a procedure to model an ultra wide-bandwidth (UWB) microstrip monopole antenna. The proposed antenna is composed of three different lengths of semi-circular shapes connected with circular disk and half circular modified ground plane. The proposed antenna has a size of 50 × 50 mm2 on a low-cost FR4 substrate. The antenna demonstrates impedance bandwidth of −10 dB extended from 1.5 to 11 GHz with discontinuous bandwidth at different interior operating bands. Two pairs of split ring resonator as metamaterial structure cells are inserted closely located from feeding transmission line of the antenna to achieve good impedance matching over the entire band of operation and improve the antenna performance. The fundamental parameters of the antenna including reflection coefficient, gain, radiation pattern and group delay are obtained and they meet the acceptable UWB antenna standard. High-frequency structure simulator ver. 14 is used as full-wave electromagnetic solver then the prototypes are fabricated and measured. Results show that the antenna is very suitable for the applications in UWB as well as wireless communication systems.

By using a metasurface (MS) structure, a linearly polarized wave is converted to circularly polarized waves. Both right- and left-handed circular polarizations (RHCPs and LHCP) are obtained by a simple configuration in the proposed structure which consists of 16 unit cells arranged in a 4 × 4 layout. Each unit cell contains five horizontal and parallel strips embedded in a rectangular frame in which a single diagonal strip is placed from one corner to the opposed one. It is shown that the orientation of the diagonal line determines the handedness of the converted signal to be either LHCP or RHCP. In order to show the working conditions of the MS structure, scattering parameters are found for both co-polarized and cross-polarized responses. Axial ratio, an indicator for polarization conversion, is then obtained by dividing cross-polar response to co-polar response to demonstrate the transformation. The structure works for horizontally and vertically polarized linear waves in a wide band frequency range which is approximately 510 MHz. Since the suggested MS model is composed of a simple geometry for polarization conversion, it can be easily adjusted in any desired frequency bands for a variety of applications from the defence industry to medical, education, or communication areas.