Over the last few decades, far-field RF-based wireless power beaming (WPB) has been a topic of interest for the microwave and the antenna engineering communities alike. This interest is in part due to the dire need for such a system for applications, ranging from biomedical to drone charging. This paper provides a comprehensive review of the published research on WPB for the last 20 years.

Midfield wireless power transfer (WPT), using frequencies ranging from sub-GHz to 2 GHz, has recently been introduced as an efficient method to wirelessly transmit power to compact implanted devices. The currently developed WPT transmitters and implantable receiver antennas are not specifically optimized to accommodate the diverse characteristics of the real human body. In this paper, more than 30 multilayered tissue realistic models, based on real CT images of humans, were simulated to define the optimal frequency.

A Schottky barrier (SB) gate N-Polar GaN-on-sapphire deep recess high-electron-mobility transistors (HEMTs) is reported. A device with a 50 nm gate length demonstrates the highest N-Polar deep recess HEMT peak fT of 176 GHz and peak fMAX of 307 GHz. A device with 77 nm gate length has a linear gain of 10.5 dB, 50.2% peak power-added efficiency (PAE) with 2.8 W/mm power and 3.2 W/mm peak power with 46.3% PAE and 6.1 dB compressed gain at 94 GHz.

Implementing high-gain antennas operating at THz frequencies relies significantly on dependable microfabrication technologies. Due to the advantages of high precision, low cost, and high uniformity, this article presents a 1.0-THz 64x64-element high-gain metal-only transmit-array (TA) antenna fabricated using ultraviolet photolithography techniques in conjunction with micro electroforming (collectively, UV-LIGA). The fabricated TA prototype is experimentally validated. The maximum gain is 36.47 dBi, and its corresponding aperture efficiency is equal to 25.96%. The measured 3-dB gain bandwidth is from 0.79 to 1.03 THz.

This letter presents a novel inverse design method for substrate-integrated waveguide (SIW) devices. Based on the internal multiport method (IMPM), the metallic via arrangement in the SIW structure is converted to a numerical optimization problem on a binary-option vector. By inputting the expected device performance, a satisfying via implementation can be automatically generated aided by the numerical optimizer, without sophisticated structural analysis and repeated full-wave simulation. Application examples are shown to verify the effectiveness and efficiency of the proposed method.