A compact high-performance dual-reflector millimeter-wave imaging antenna with a 20/spl times/20 degrees square field of view

Several remote sensing applications require compact antennas capable of providing high-gain and narrow beamwidths over a wide frequency band and field of view. A high performance offset dual-reflector imaging antenna with a clear circular entrance aperture of 200 wavelengths in diameter, operating at 94 GHz, is presented. The antenna has concave ellipsoidal and hyperboloidal main- and sub-reflectors, respectively, with shape, location, and orientation determined by numerical optimization. It is capable of providing, across its entire 20/spl deg//spl times/20/spl deg/ square field of view, a practically constant radiation pattern with a half-power beamwidth of about 0.32/spl deg/, less than 1.4 dB of gain variation, and crosspolarized peak radiation more than 40 dB below the co-polarized peak value.