A beam-scanning dual-polarized fan-beam antenna suitable for millimeter wavelengths

The design and testing of a beam-scanning pillbox antenna for use in a 200 GHz imaging system is presented. The antenna features a rotating subreflector that scans the antenna's fan beam and a multimode structure that reduces ohmic loss and allows use of two orthogonal polarizations. The antenna has an aperture size of 450 x 5 mm, half-power beam widths of approximately 0.4 degrees and 18 degrees and a beam-scan range of 10 degrees. The gain of the antenna was measured to be greater than 33 dBi for both polarizations. The radiation patterns of the pillbox antenna have been measured in the radiating near field using an outdoor range. Good agreement between measured and calculated patterns has been obtained.