Kazuyuki Seo

Microstrip-to-waveguide transition using waveguide with large broad-wall in millimeter-wave band

Broad-wall connected microstrip-to-waveguide transition using a waveguide with large broad-walls is proposed. Maximum width of the waveguide where higher order mode dose not propagate is used. The dimension of the rectangular patch element is examined to have optimum width for wideband. Moreover, the distance from the edge of the broad-wall of the waveguide to via holes is also examined to have optimum length for wideband. A numerical investigation of a transition shows appropriate parameters. Proposed transition has insertion loss less than 0.28 dB from 77 GHz to 81 GHz, and a bandwidth of 18.2 % (14.4GHz) for reflection coefficient below −15 dB.

High coupling radiating element using impedance transform stub for microstrip comb-line antennas in the millimeter-wave band

A novel high coupling radiating elements using an impedance transform stub are developed for microstrip comb-line antennas. In the design of low-sidelobe microstrip comb-line antennas with small numbers of element, array element with large coupling of the antenna around the input port is required. The radiating edge impedance of the rectangular microstrip antenna is transformed to adequate low impedance around the input port by the impedance transform stub. Then, high coupling is achieved. The coupling power is controlled from 6 % to 70 %. The performance of low-sidelobe 6-elements comb-line antenna with our proposed high coupling radiating element using impedance transform stub was demonstrated in this paper.