Jiang-Qiao Ding

A novel W‐band narrowband waveguide diplexer based on an all‐resonant structure is proposed, designed for high‐performance integrated transceiver systems in the millimeter‐wave and sub‐terahertz bands. Unlike conventional manifold‐based diplexers, the diplexer employs a common resonant junction to directly connect the two channel filters, enabling a compact configuration with high channel isolation and steep roll‐off. The synthesis is based on the coupling matrix principle, and the main novelty lies in a hybrid coupling mechanism, in which different inverter types are introduced at different locations to suppress spurious modes. An E‐plane stub is adopted in the strong‐coupling sections to facilitate high‐yield CNC milling. Experimental results of the aluminum diplexer show center frequencies at 85.6 and 93.4 GHz with fractional bandwidths of 3.5% and 3.2%. The measured insertion losses are 0.9 and 0.85 dB, respectively. These results demonstrate that the proposed design provides an effective solution for high‐frequency electronics and millimeter‐wave system applications.

This study explores the influence of microbridge dimensions on the electrical properties of superconducting titanium (Ti) bolometers. Devices with microbridge sizes ranging from 1 μm tttttttt 1 μm to 32 μm × 32 μm were fabricated and characterized. Resistance-temperature (R-T) measurements show that the critical temperature of the bolometers increases as the microbridge length decreases below 2 μm, corresponding to a length up to approximately 20 times the coherence length and 870 times the electron mean free path. This behavior is attributed to the longitudinal proximity effect. Analysis of the current-voltage (I-V) characteristics measured at different bath temperatures shows that the thermal conductance does not scale linearly with the microbridge area. This nonlinearity is likely caused by incomplete suppression of electron diffusion by the superconducting niobium (Nb) contacts as the Ti film thickness exceeds the proximity length within the Ti layer. This result suggests that optimizing the Ti film thickness could suppress electron diffusion and improve the overall performance of superconducting Ti bolometers.

The development of next-generation terahertz (THz) transmitters and receivers based on 3D stacked packaging technology relies heavily on the integration of high-performance waveguide directional couplers. This paper presents an accurate and efficient method based on the mode-matching method (MMM) for the rapid analysis of a branch waveguide coupler fabricated through a silicon-based 3D stacking process. In contrast to the traditional method using the finite-element method (FEM) in HFSS, which is cumbersome and time-consuming, the proposed method offers orders-of-magnitude speed improvement. It is especially well-suited for large-scale uncertainty error analysis and statistical evaluation of THz waveguide couplers and related components. This theoretical MMM is validated through an experiment by characterizing a deep reactive ion etching (DRIE) fabricated and 3D stacked 220 GHz waveguide coupler.

A terahertz (THz) waveguide directional coupler with weak coupling based on a single quartz chip is proposed in this letter. Three radial microstrip probes are adopted to offer a weak coupling, meanwhile corrugated structures are used to prevent the crosstalk between probes. Both probes and decoupling circuits have been integrated on the single quartz chip to replace the un-machinable waveguide branches in a traditional weak coupler. Besides, the angle and radius of each radial probe can be adjusted to obtain different coupling coefficients. Two quartz chip prototypes with different coupling coefficients of −20 and −17 dB have been produced and mounted in the WR-3.4 waveguide blocks. The measured coupling coefficients are $-18$ ±2 dB and $-15$ ±2 dB, respectively, which agree well with the simulation across the wideband of 200–290 GHz. This exploitation of a single quartz chip with adjustable coupling has exemplified the innovation of weak coupler design, which can meet the application requirements of THz sideband-separating receivers.

太赫兹空间探测系统正向多通道、多谱段和超宽带方向快速发展. 提出基于波导混合网络型的WR-4频段全频带双工器, 用于双频段固态系统中本振信号的合路泵浦. 该双工器基于混合网络的防反射、高隔离耦合等特性, 结合高阶数低通滤波器级联实现, 整体结构鲁棒, 且易于计算机数控(CNC)制备并系统集成. 研究内容主要包括WR-4全频带覆盖混合网络型双工器的原理设计, 分立单元器件混合器、滤波器的电路设计, 混合网络型双工器的电路综合、优化及其E面分裂式CNC铣削加工. 实测结果表明, 该WR-4频段双工器能够实现全频带划分, 含170～210 GHz和210～260 GHz两个通道, 通道内插损低至–1.5 dB和–1 dB, 其中一个通道的隔离高达50 dB, 所有测试结果与仿真数据高度一致. 此外, 该固态双工器电路具有易结构加工、易系统集成、易通道扩展和易频率拓展等特点.

In this work, two WR-3 band waveguide diplexers based on symmetrical H-plane and E-plane Y-junctions are developed, fabricated, and compared to highlight bandwidth performance. Both symmetrical H-plane and E-plane Y-junctions are first analyzed to determine the conditions for implementing wideband waveguide diplexers. Then a mid-band H-plane diplexer-I and a wideband E-plane diplexer-II are designed and demonstrated through CNC-milling technology. The measured results of H-plane diplexer-I show central frequencies of 251.5 GHz and 294 GHz, 3 dB fractional bandwidths (FBWs) of 5.6% and 3.3%, as well as insertion losses (ILs) of about 2 dB. The practical E-plane waveguide diplexer-II has achieved central frequencies of 264.5 GHz and 309 GHz, 3 dB FBWs of 11.4% and 6.2%, low ILs of 1.5 dB, as well as high isolation exceeding 50 dB. All the measured performance agree well with the simulation, verifying that the symmetrical E-pane Y-junction is optimal for the wideband waveguide diplexer. Additionally, such compact and scalable THz waveguide diplexers for future transceivers can meet the current CNC manufacturing constraints.

This paper presents a high gain, broadband silicon micromachined diagonal horn array antenna for the 190 GHz to 250 GHz frequency band. The antenna array is configured to be built from 34 silicon layers. The upper 25 layers of silicon wafers create an 8×8 diagonal horn array antenna and the lower 9 layers form the feed network. The diagonal horn is selected as a radiation element for its 45° polarization direction, which suppresses side and grating lobes in the E-plane and H-plane after array formation. Polarization converters are innovatively employed in the feed network to resolve the issue of opposite polarization from waveguide T-junctions. In order to meet the silicon micromachining criteria, all diagonal horns and the feed network are step-profiled designed based on silicon wafer thickness. The 34 silicon layers are aligned and fixed by CNC-milling metal tooling. Monte Carlo analysis is utilized to quantify the interlayer offset errors introduced during the assembly of the wafers. The measurement results are within the error allowance. The antenna achieves a peak gain of 30.9 dBi and a working frequency bandwidth of 27%. Characterized by highly directive radiation patterns with low side lobe levels in the E-plane and H-plane, the antenna is well-suited for next-generation THz point-to-point communication systems.

太赫兹固态肖特基谐波混频技术是空间天文、行星、大气探测的重要手段, 显然研究太赫兹单片集成谐波混频器具有重要意义. 本文克服了传统混合集成方法(即将分立的肖特基二极管与石英匹配电路胶接而成)存在的装配难、热效应不平衡、可靠性差等系列问题, 基于全自主国产砷化镓流片工艺线, 完成了550 GHz频段单片集成谐波混频器的研制与验证. 二极管设计方面, 建立精确的肖特基变阻管非线性和3D模型; 匹配电路方面, 采用典型的减高波导、高低阻抗悬置微带线(实现RF与LO信号的隔离)、矩形探针等结构, 结合场路分析方法, 实现最简化匹配电路设计; 整体电路含二极管对集成在3 μm厚的GaAs (Gallium Arsenide)薄膜上, 并通过两侧的梁氏引线实现与腔体的固定安装. 测试结果表明: 混频器模块在548～572 GHz单边带变频损耗优于13.4 dB, 并基于此结果实现了设计的反馈仿真研究.

A conformal circularly polarized H-plane horn antenna with broadband and low-profile characteristics is proposed in this paper, which is integrated with quasi-Yagi and wrapped around a hollow cylinder. The H-plane horn based on bent corrugated substrate integrated waveguide (BCSIW) technology and the quasi-Yagi with fan-shaped driving elements provide the vertical and horizontal linear polarized waves respectively, which generates circularly polarized radiation combining with the suitable phase delay provided by the transition section. The proposed antenna is wrapped around a hollow metallic cylinder with radius of 100 mm and height of 90 mm. The measured voltage standing wave ratio (VSWR) of the fabricated antenna is less than 2.0 in the frequency range over 9.4 GHz (81%) while the axial ratio (AR) is below 3 dB from 9.4 GHz to 21.7 GHz (78%). The antenna also exhibits stable radiation pattern with peak gain of 12.1 dBi and a cross-polarization below -17dB over the whole frequency range. It is observed that the measured results agree well with simulated ones.