This letter presents a vertically polarized omnidirectional antenna designed for operation within the 50-75 GHz (V-band) frequency range. The compact antenna structure and wide working bandwidth are achieved through the use of a radial waveguide radiator and an axial intermediate converter. The measured results from the manufactured prototype agree well with the simulated data in terms of radiation pattern and return loss. The antenna exhibits a 3 dB beamwidth in the elevation direction exceeding 30 $^\circ$ and a return loss greater than 10 dB across the working band. Owing to its wide bandwidth and omnidirectional radiation performance, the proposed antenna emerges as a promising candidate for indoor wireless communication system.

We report a room-temperature, low output impedance, broad intermediate-frequency (IF) bandwidth field-effect terahertz detector based on an AlGaN/GaN high-electron-mobility transistor (HEMT) integrated in a metal waveguide. The waveguide detector equips a pair of quasi-Yagi antenna probes that are used to couple the terahertz energy to the HEMT channel. The gate is configured as an asymmetric edge-coupled coplanar waveguide transmission line. This terahertz electric field is asymmetrically distributed in the channel along the edges of the transmission lines. The responsivity and noise for direct and heterodyne detections are characterized and analyzed at different local oscillator (LO) powers. The noise-equivalent power in direct detection is below 189 pW/${\text{Hz}}^{1/2}$ . Operated in a heterodyne mode with a LO power of −3 dBm, the detector offers a conversion loss less than 55 dB in a frequency band of 320–340 GHz. The channel in a form of transmission line performs the broad IF bandwidth, which is increased to gigahertz range (3 GHz), and reduces the output impedance to 377 Ω which is about 20 times lower than previously reported. The transmission-line impedance could be optimized together with the distribution of the terahertz electric field in the gated channel to reduce the conversion loss.

This paper proposes a compact W-band antenna-in-package (AiP) design for a phased array front-end module. A slot-coupled stacked patches structure is developed to address integration challenges and enhance bandwidth limited by the thin substrate. The antenna is optimized by particle swarm optimization (PSO) algorithm and manufactured by cost-effective modified semi-additive process (mSAP). Experimental results from an 8 × 8 phased array module demonstrate consistent performance, including $\pm 30 ^{\circ }$ beam scanning ability, low scan gain loss (< 2 dB) and low cross-polarization(< -20 dB) with a maximum measured EIRP of 54.8 dBm. This work provides a scalable and cost-effective solution for the integration of millimeter wave phased array systems.

A Ka-band dual-polarization magnetoelectric (ME) dipole antenna array based on three-dimensional (3D)-printed technology with low sidelobe level (SLL) is proposed in this paper. The metal posts and cross-slots are explored to build a novel subarray with 2 × 2-unit ME-dipoles as the basic element. Creatively, a square waveguide to cross-slots transition with a pyramid horn cavity structure is investigated to feed the ME-dipole subarray. Furthermore, two types of power-tapering corporate-feed networks with laminated structures are used to design an 8 × 8-unit low-SLL array. The fabricated array has a relative bandwidth (VSWR < 2) of 14.3% and 17.1%, with a realized gain higher than 25.8 dBi and 26.1 dBi for the H-pol. and V-pol., respectively. The maximum radiation efficiency for both arrays is 73.2%. The measured first sidelobe levels are less than –17.5 dB for both polarizations. With competitive performance and low fabrication cost, the proposed dual-polarization ME-dipole antenna array would be valuable for polarization-agile radar and communication systems.

A sextuple band circularly polarized (CP) shared- aperture antenna (SAA) with a small frequency ratio (FR) is presented in this paper. The SAA consists of a wideband scanning array and five narrow-band antennas. For a high integration, the stacked, interlaced and structure-reused schemes are employed comprehensively. To solve the problem of the insufficient area of the lower antenna to support the upper antenna in a stacked scheme, the metal column is introduced and it can also shield out the effects of feeding coaxial lines on the performance of the lower antenna. By loading the cavity, the degraded performance at the low elevation angle can be compensated. The SAA has a high ratio of aperture reduction compared with tradition multiple separate antennas, while keeping a lower profile. It can achieve 2D beam steering in a scanning range of ±45°.The prototype was fabricated and the measured results are consistent with the simulated ones. This SAA is well suited for navigation and wireless communication.

This article presents an ultra-compact and broadband Wilkinson power divider/combiner (WPDC) designed for large-scale phased arrays. To minimize the chip area, a shortened transmission line (T-line) topology using a metal-stacked inductor is introduced into the two stages. Furthermore, to address the isolation bandwidth (BW) limitations, two sections of shortened T-lines are adopted and innovatively implemented within a single inductor footprint by utilizing a magnetic coupling self-canceling technique. Detailed analysis and design flow of the proposed network synthesis are provided, demonstrating a 67% area reduction. Moreover, a novel shielding topology is employed to simultaneously enhance isolation between combiners and ensure amplitude/phase uniformity across distribution branches. To verify the proposed technique, a C–X-band WPDC, consisting of two 1:4 power combining units dedicated to intermediate frequency (IF) and local oscillator (LO) bands, respectively, is fabricated in a 65-nm bulk CMOS process. The prototype exhibits a measured insertion loss (IL) of within 3.2/3.4 dB and isolation exceeding 24.9/26.0 dB across the IF (6–10 GHz)/LO (8–12GHz) band. Notably, isolation greater than 60 dB is attained between IF and LO crossover networks, which is validated in antenna-in-package (AiP) measurements. This design features an ultra-compact core area, a highly competitive fractional isolation BW, and an outstanding branch isolation among state-of-the-art reported works, rendering it well-suited for area-constrained large-scale and multibeam phased-array systems.