Single- and dual-polarized millimeter-wave slot-ring antennas

Single- and dual-polarized dielectric lens-supported slot-ring antennas have been developed for operation at millimeter-wave frequencies. The antennas are fed with a coplanar waveguide (CPW) to be compatible with uniplanar mixers and low-noise amplifiers, and the feedline is shown to have a minimal effect on the antenna performance. The measured antenna patterns agree well with theoretical results and have symmetric main beams, low sidelobe levels (<-15 dB), low cross polarization (<-20 dB), and 27 dB directivity. A 2/spl times/2 array of single-polarized slot-ring antennas for monopulse applications demonstrates excellent patterns at 94 GHz with -3 dB crossover power levels in both elevation and azimuth scans. The dual-polarized slot ring antenna patterns are nearly identical to those of the single-polarized antenna, and two-port isolation is as low as -25 dB. The dielectric lens-supported slot-ring antenna is an excellent candidate for compact, low-cost millimeter-wave systems with fixed or variable polarization capabilities.