Inertialess Polarization Scanners

摘要

The report discusses the principles of operation, the design, and the performance of a pair of X-band polarization-agile radar antennas, one for transmitting and one for receiving. These antennas are compatible with an existing pulse-Doppler radar and utilize front-fed 4-foot paraboloidal reflectors. The direction of linear polarization of these antennas can be rotated in digital increments on a pulse-to-pulse basis at prf's as high as 50 KHz. An electronic programmer permits the manual selection of any one of 32 polarization directions or the automatic sequencing of the available polarization directions in a variety of operational modes. A change in polarization is accomplished in less than two microseconds and the total insertion loss of each complete antenna is less than 1.0 dB. The antennas track within 7 degrees for all polarization directions with polarization purity greater than 23 dB for frequencies between 9.8 and 10.25 GHz. The gain, VSWR, and antenna patterns of the polarization-agile antennas are comparable to single-polarization antennas of the same size. (Author)