This paper presents a 31 GHz integrated power amplifier (PA) in 28 nm Fully Depleted Silicon-On-Insulator Complementary Metal Oxide Semiconductor (FD-SOI CMOS) technology and targeting SoC implementation for 5 G applications. Fine-grain wide range power control with more than 10 dB tuning range is enabled by body biasing feature while the design improves voltage standing wave ratio (VSWR) robustness, stability and reverse isolation by using optimized 90° hybrid couplers and capacitive neutralization on both stages. Maximum power gain of 32.6 dB, PAEmax of 25.5% and Psat of 17.9 dBm are measured while robustness to industrial temperature range and process spread is demonstrated. Temperature-induced performance variation compensation, as well as amplitude-to-phase modulation (AM-PM) optimization regarding output power back-off, are achieved through body-bias node. This PA exhibits an International Technology Roadmap for Semiconductors figure of merit (ITRS FOM) of 26 925, the highest reported around 30 GHz to authors' knowledge.

In this paper, the design of a miniature antenna dedicated to the detection of airliners through the demodulation of Automatic Dependence Surveillance-Broadcast system (ADS-B) signals is presented. This antenna is designed for being embedded on the top of a drone in order to detect and avoid collisions with airliners. This antenna consists of an array of Planar Inverted-F Antennas, a quadrature feed network (FN) and a reflector plane (RP). The FN is designed to have output signals with the same amplitude and a 90° phase difference between each other. It achieves circular polarization and maintains the axial ratio of the antenna under −3 dB at the desired frequency (1.09 GHz). The antenna with the FN was manufactured and characterized. It weighs approximately 145 kg with its RP. The measured gain of the proposed antenna is about +3.7 dBi. To validate the design, the manufactured antenna was tested with a Universal Software Radio Peripheral for the processing of ADS-B signals at the French National Microwaves Days 2019 (JNM) student contest. The detection of airliners can reach up to 437 km.

A radio frequency (RF) 3-bit digital power amplifier (DPA) is described in this paper. It consists of three RF amplifiers connected at their outputs with a transmission line (TL) network. The three amplifiers are designed for different output powers (POUT). The TL network allows them to load-pull one other to achieve eight different amplitude states by alternatively enabling and disabling the amplifiers via their gate bias. A prototype was designed in the National Instruments' Microwave Office (MWO) for 500 MHz with the aid of a genetic algorithm to optimize the TL network for all seven active (on-) states. The optimizer efficiencies goals were based on data derived from load-pull simulation. The POUT goals were based on a 1 Vrms step-size. In simulation, ≥50% efficiency was achieved at all on-states with 29.7 dBm peak POUT. A practical prototype based on the simulation achieved an efficiency of ≥40% over all seven on-states. A peak POUT of 28.9 dBm was achieved, with the lowest state at 22.4 dBm.

A separately-designable diplexer with multiple transmission zeroes (TZs) using common stub-loaded stepped impedance resonator (SIR) is proposed. The common stub-loaded SIR operating in third harmonic (f3) and fifth harmonic (f5) is used for designing the two diplexer channels. The stub is loaded at the voltage-null point of f3 of the SIR. It can separately control f5 but has no effect on f3 so that the two channels can be separately designed. Meanwhile, the input port is tap-connected to the common stub-loaded SIR, which necessarily produces a TZ between f3 and f5, existing in both channel filtering responses. By properly choosing coupling schemes of the two channels, more TZs are realized at the desired locations. Thanks to the generation of the multiple TZs, both passband selectivity and isolation between the two channels are improved significantly. For demonstration, a diplexer operating at 2.22 and 2.95 GHz is designed, fabricated, and measured. The simulated and measured results are presented, showing good agreement.

This paper reports an integration of dual band microstrip antenna with thin film amorphous silicon solar cell which creates a wearable system to harvest microwave energy. The multiple layers in the encapsulation of the thin film solar cell are used as a substrate for microstrip antenna. The rectifier and matching circuit are designed on cotton jeans material and the whole system is mechanically supported by the foam of 5 mm thick. The performance of the antenna is studied for the mechanical bending condition. The device has maintained good power conversion efficiency. The efficiency of the voltage doubler is tested by varying radio frequency power levels from −30 to10 dBm. The voltage doubler conversion efficiency at 1.85 and 2.45 GHz are 58 and 43%, respectively, for a load of 7.5 kΩ for an input power level of −5 dBm.

In this work, we propose a broadband, polarization-insensitive and wide incident angle stable metamaterial absorber (MA) based on the resistive film. The absorber consists of a three-layer structure with each layer of dielectric substrate printed with different shapes of resistive film. The multilayer structure not only extends the absorption bandwidth but also maintains high absorption under large wave incident angles. Numerical simulation shows that the absorptivity of a normal incident wave is above 90% in the frequency range 2.34–18.95 GHz, corresponding to a relative absorption bandwidth of 156%. Moreover, the whole MA structure has a total thickness of 11.3 mm, corresponding to 0.09 λ0 at its lowest absorption frequency. Due to the high symmetry of the structure, the absorber has good polarization insensitivity. In addition, for both transverse electric and transverse magnetic incidence, the proposed absorber achieves an absorptivity of more than 80% at incident angles of up to 45° and thus has good stability for wide incident angles. The absorption principle of the absorber is analyzed by the surface current and power loss density distribution. Parameter analysis is also performed for bandwidth optimization. Due to its advantages of wideband absorption with high efficiency, the proposed absorber has the potential to be applied to the energy-harvesting and electromagnetic stealth fields.

This paper discusses the design and fabrication of a low-profile Hilbert-shaped metamaterial (MTM) array-based antenna, forming a rectangular patch with partial ground plane backing; the rest is slotted with traces for RF energy harvesting. The antenna is mounted on a 28 mm × 32 mm indium nickel oxide polymerized palm fiber (INP) substrate and compared to the identical one based on FR4 substrate. The two prototypes are printed with silver nanoparticles. Numerical and experimental tests are applied to the antenna performance in terms of S11 and radiation patterns. The obtained antenna gain bandwidth product of the INP prototype is found to be significantly better than the FR4 prototype. The proposed INP antenna gain at 5.8 and 8 GHz frequencies is found to be about 4.56 and 7.38 dBi, respectively, while the FR4 antenna gain is found to be 4.56 and 6.85 dBi at 5.8 and 8 GHz, respectively. Finally, the resultant DC voltage and the efficiency of conversion from harvested RF energy are measured experimentally at 5.8 and 8 GHz for both proposed prototypes.

A compact multiple input multiple output (MIMO) antenna operating at 2.45 GHz industrial scientific and medical band is presented for wearable devices. Open-end slotting is used to miniaturize the antenna dimensions. Inverted U-shaped ground stub is incorporated to reduce mutual coupling. On-body performance is analyzed on a three-layered equivalent tissue phantom model. The wide bandwidth of 300 MHz and port isolation of 30 dB are obtained from measured results. The antenna shows the efficiency of 40% and directivity of 4.56 dBi when placed at a gap of “s” = 4 mm from the body. Broadside radiation pattern and low specific absorption rate make the antenna suitable for on-body communication. Further, diversity performance is measured in terms of envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL). The value of ECC is 0.025, DG is 9.98 dB, and CCL is 0.12 bits/s/Hz at 2.45 GHz. Antenna robustness is examined by bending the structure at different radii along the x-axis and y-axis. Performance of the proposed structure is reliable with structural deformation.

In this research, a compact dual band-notched (DBN) super-wideband (SWB) coplanar waveguide-fed antenna with high bandwidth (BW) dimension ratio of 7427.4 has been presented. The proposed antenna covers a very wide frequency range from 2.8 to 40 GHz (BW ratio of 14.28:1) with |S11|<−10 dB. The overall antenna size is 20 × 14 × 1.6 mm3 which consists of an FR4 substrate with a dielectric constant of 4.4, a shovel-shaped radiating patch and the symmetric stair-shaped ground plane. The DBN characteristics are achieved by employing a pair of C-shaped and circular slots on its shovel-shaped radiating patch to reject the interferences caused by two WiMAX (3.7–4.7 GHz) and WLAN (5.7–6.4 GHz) bands. The notched frequency bands can be controlled by changing the radii of slots. The SWB property of the antenna is obtained by using a symmetric stair-shaped ground plane and also a shovel-shaped radiating patch. The measured results of the fabricated prototype in frequency-and time-domain are also presented and compared with the numerical results. The results indicate that the antenna has good performance over the entire operating BW (173.8%) which makes it very potential candidate for modern SWB applications.

Two configurations of a modified feather-shaped antenna element are proposed for super wideband (SWB) multiple-input multiple-output (MIMO) applications. The antenna element geometry comprises of a circular slot-loaded feather-shaped radiator and rectangular notch-loaded quarter elliptical coplanar waveguide ground plane. An operating bandwidth of 4.4–51.5 GHz with inter-port isolation, S21 ≥ 15 dB for spatial diversity configuration, and 3.8–51.5 GHz with S21 ≥ 15 dB in pattern diversity configuration are achieved. The footprints of the antenna configurations are 17 × 33 and 31 × 31 mm2. Both configurations exhibited an envelope correlation coefficient of <−20 dB. The proposed MIMO configurations are fabricated and experimentally validated. The designed antenna configurations are SWB and compact.