A 35-GHz transmitter (TX) and receiver (RX) front end in CMOS technology for Ka-band frequency-modulated continuous wave (FMCW) phased-array radar transceivers are presented in this article. While typical FMCW phased-array radar transceivers use RF-path phase-shifting scheme for both TX and RX front ends, the Ka-band TX and RX front ends presented in this article are designed for TX-analog and RX-digital beamforming phased-array radar system. The link budget for the Ka-band phased-array radar transceiver is investigated. In order to improve the TX output power level, a power amplifier (PA) with a four-way power splitter/combiner is introduced. The detailed analyses and design considerations of the PA are investigated. The proposed TX and RX front ends are implemented and fabricated in a 1P9M 65-nm CMOS technology. The measured TX output power is 19 dBm. To the best of authors' knowledge, it is the highest output power FMCW module at the Ka-band using CMOS technology reported so far. The RX achieves a conversion gain of 29.6 dB. The TX occupies 1.42 mm² and consumes 588 mW. The RX occupies 0.59 mm² and consumes 72 mW.

The smart unmanned aerial vehicle (UAV) with a mini-SAR payload provides an advanced earth observation capability for target detection and imaging. Simiar to large-scale SAR, mini-SAR also has an increasing requirement for high resolution and wide swath. However, due to the low cruising altitude of UAVs, small coverage angles in the direction range, and the insufficient operating range of mini-SAR, expanding the swath has become an urgent problem for mini-SAR. To solve this problem, this paper proposes a W-Band active phased array miniaturized SAR (APA mini-SAR), whose scanning capacity has been proven on the multi-rotor UAV platform. Many efforts, including the novel active phased array antenna scheme, the sparse triangular arrangement of antenna elements, the wideband chirp source, and the three-dimensional integration technology, have been made to develop this APA mini-SAR for the first time in the W-Band. The volume of this APA mini-SAR is 69 × 82 × 87 mm³, with a weight of 600 g. Combined with a new motion compensation strategy and the ω-k imaging algorithm, the focused image is finally obtained. Experiments have been conducted, and the results indicate that this APA mini-SAR has a resolution of 4.5 cm, the imaging swath is three times that of the traditional single-channel mini-SAR, and the operating range is increased to 800 m.

Radio frequency tag detection by radars has received much attention in recent years for its long working distance and high positioning accuracy. This study proposes a novel method that combines synthetic aperture radar (SAR) system with metamaterial-modulated tags that can simultaneously achieve tag positioning and imaging. However, the high working frequency of SAR and the noncoherence between SAR and tag signals pose great challenges to the design and focused imaging of tag. Based on the mathematical model establishment of modulated target imaging, a new transmission waveform strategy and signal processing method were developed for simultaneous focused imaging of scenes and tag that were verified through simulation. Meanwhile, a tag-designing method based on metamaterial modulation was proposed, and direct loading of modulation signals onto radar echoes in the millimeter-wave band was realized. Additionally, an experimental system based on vehicle-mounted miniaturized SAR (Mini-SAR) and metamaterial tag was established. The experimental results indicated that focused images of the tag and environment were simultaneously obtained, and the SAR system realized long-distance, accurate detection, and positioning of the tag, with a working distance of 300 m, a range resolution of 27 cm, an azimuth resolution of 18 cm, and a positioning accuracy of 1.5 cm.

In order to expand the applications of the traditional Vivaldi antenna by addressing the low gain of the traditional Vivaldi antenna, this paper combines the phase distribution of the Vivaldi antenna aperture based on the analysis of the transmission characteristics of a dielectric unit by utilizing the advantages of artificial electromagnetic material. A more reasonable method of loading a dielectric lens is proposed and utilized in combination with edge grooving. A comparison of the results shows that the antenna operates in the frequency range of 4 to 16 GHz. The low-frequency boost is approximately 3 dB, and the high-frequency boost is approximately 9.6 dB.

The development of 28-GHz CMOS phased-array transceivers for 5G new radio applications has been grown rapidly in recent years. This paper discusses the challenges and requirements in the design of the 28-GHz CMOS phased-array transceiver RFICs. The key architectures of analog phase shifting are examined in detail. Several RFICs of the 28-GHz CMOS phased-array transceiver are presented to give a brief overview on the state-of-the-art work.

The synthetic aperture radar (SAR) mounted on unmanned aerial vehicles (UAVs) can efficiently and rapidly acquire high-resolution geographic remote sensing data. However, the limited payload capacity and power consumption of UAVs present a challenge for the application of traditional SAR real-time imaging processing platforms based on DSP or GPU. In this paper, a real-time processor that utilizes the Xilinx Zynq Ultrascale+ZU9EG MPSoC is proposed and successfully applied to a W-band Mini-SAR system. Several essential technologies, including SAR data preprocessing, high-energy-efficient real-time processing, and lightweight motion compensation, are utilized to develop the real-time processing Mini-SAR for use in small UAVs. The total weight of the entire system is only 724 grams, and its power consumption is 38.3 watts. During the UAV flight test, the system is capable of producing SAR images with a resolution of 0.1 meters at a size of 4K x 4K in just 4.5 seconds. The discrepancy between the imaging results and the ground post-processing is less than 10^-4.