A Simple Through-Hole Based Transformer between Microstrip Line and Post-Wall Waveguide for Millimeter-Wave Applications

Yusuke UEMICHI  Ryouhei HOSONO  Ning GUAN  Jiro HIROKAWA  Makoto ANDO  

IEICE TRANSACTIONS on Electronics   Vol.E97-C   No.10   pp.941-947
Publication Date: 2014/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E97.C.941
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Microwave and Millimeter-wave Technologies)
post-wall waveguide,  transformer,  liquid crystal polymer,  millimeter-wave,  

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We proposed a through-hole based transformer between microstrip line and post-wall waveguide (PWW). The transformer is based on a through-hole which is electrically separated from top and bottom broad walls of a waveguide by ring-shaped spaces. The proposed transformer shows a considerable merit compared with a conventional one based on blind-via in terms of fabrication and cost because it can be realized by through-holes in general printed-circuit-board technology. We selected liquid crystal polymer (LCP) as the material of substrates because of its lower dielectric loss and easy fabrication. The transformer was fabricated and measured. The loss associated with the mode conversion is estimated to be around 0.32 dB, and the bandwidth for a reflection smaller than -15 dB is 8 GHz, i.e., from 59 to 67 GHz.