Frequency-property improvement of a planar waueguide array antenna for compact range application

Attempts for constructing an inexpensive compact range environment have been made so far by the authors [1]-[2]. The environment consists of a 3 cubic meter anechoic chamber and a plane wave generating source antenna made of WRJ-10 waveguide arrays. The latter, however, had a narrow frequency range of operation very close to f=12 GHz because of the nature of the waveguide structure and the feed system. The source antenna the authors are considering here is the arrays of waveguides with slots on the E-plane wall of the waveguides. By combining 48 of these waveguides, the source antenna with its approximate aperture dimensions being 1200 mm × 1200 mm is constructed. This waveguide array antenna is to be fed by a corporate feed system so that an equi-phase /equi-amplitude feed at each waveguide end is realized over the X-band frequency range. Since the wave front of a waveguide slot array become tilted when excited by a wave different from the designed frequency, slight rotation of the source antenna system is being planned. In this paper, as a first step of fabricating the planar array, the basic properties of the element waveguide are investigated.