Millimeter-Wave Waveguide-to-Microstrip Transition With a Built-In DC/IF Return Path

• Published in: IEEE transactions on microwave theory and techniques Vol. 69; no. 2; pp. 1295 - 1304
• Main Authors: Wu, Chengkai, Zhang, Yong, Xu, Yuehang, Yan, Bo, Xu, Ruimin
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: <italic xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">E -plane probe; Conversion; DC/IF return path; Frequency doublers; Metals; Microstrip; millimeter wave; Millimeter waves; mode conversion; Plane probes; Probes; Rectangular waveguides; Substrates; Waveguide transitions; waveguide-to-microstrip transition; Waveguides; Wire; Wires
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2020.3041257

In this article, a novel waveguide-to-microstrip transition with a built-in dc/IF return path is proposed, in which a traditional E- plane probe is directly connected to the backshort by a thin metal wire along the axis of the waveguide. The proposed waveguide-to-microstrip transition implements an additional dc/IF return path while realizing mode conversion. Moreover, the presence of the dc/IF return path has little influence on the performance of the original E- plane probe. The operating principle is analyzed by theoretical analysis and full-wave simulation, and the design procedure of the transition is also presented. To implement the proposed dc/IF return path on different substrates, two approaches, including direct integration with planar circuits or with wire bonding technology, are developed. Furthermore, two back-to-back transition prototypes working in the millimeter and submillimeter bands were designed and characterized. The measured results are in excellent agreement with the simulations. Finally, as an application example, a 70-/140-GHz unbalanced frequency doubler adopting this structure for both dc biasing and dc grounding was designed and fabricated. Measured results show that the conversion loss of the fabricated doubler is less than 13 dB in the range from 125 to 145 GHz, and the minimum conversion loss is 11 dB at 140 GHz with 100-mW input power.