Sub-Millimeter-Wave Polarization-Independent Spatial Power Divider for a Two-Port Dual-Polarized Antenna

An antenna system is proposed that uses a novel polarization-independent spatial power divider to align the beams from two orthogonally oriented dual-polarized feeds. This antenna system uses a common aperture for transmitting and receiving and provides high port isolation while maintaining compatibility with fully polarimetric radar. Unlike conventional two antenna radar systems, a radar using this antenna does not suffer from the parallax problem. The spatial power divider is designed using an all-dielectric metasurface approach and is fabricated on a silicon wafer using standard micromachining technology. The measured device exhibits at most 0.9 dB of difference between the reflection and transmission for both transverse electric and transverse magnetic incident waves at 45 degrees incidence, over a band from 221 to 250 GHz. Conical horns are fabricated as feeds and together with the spatial power divider, a focusing lens, and microwave absorbers, are assembled in a three-dimensional-printed housing to complete the antenna system. Its measured gain is approximately 39 dB for each port and polarization, and isolation between ports is at least 40 dB for all polarization combinations over the band of interest.