Quasi-optical antenna mixer system fed by a coplanar waveguide

Abstract

The quasi-optical antenna mixer system transforms a radio frequency (RF) signal into the intermediate frequency (IF) signal as soon as the system receives the RF and the local oscillator (LO) signals spatially. This system can be expected to reduce transmission line loss, especially in higher frequency bands, such as the millimeter-wave band, because the RF transmission line is removed. In this paper, we propose a dual frequency operating microstrip antenna fed by coplanar waveguide, with a mixer diode to realize the quasi-optical antenna mixer system. It is a problem of the receiving part in conventional quasi-optical antenna mixer systems that LO incidence obstructs RF incidence because both RF and LO signals are received from one side of the system. Therefore, we construct a quasi-optical antenna mixer system that can receive the RF and LO signals separately on both sides of the substrate. To begin with, the receiving part is designed and its characteristics are evaluated with an electromagnetic simulator. Next, the system is fabricated and tested on the dual frequency operation of the receiving part and the mixing operation in the microwave band. As a result, we confirm that our proposed system functions as a quasi-optical antenna mixer. ©1998 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 82(1): 22–30, 1999.