Backscatter theory and measurements for a millimeter-wave focused-beam radar

A portable millimeter-wave, fully polarimetric, high-resolution radar that uses a focused scalar horn-lens antenna has been developed. The one-way, copolarized beam in the focal plane has a measured -3 dB spot size diameter (circularly symmetric) of 4.6 in. The focused-beam properties of the antenna give the radar high angle-angle (azimuth and elevation) resolution, and for this reason the radar has been named the flashlight radar (FLR). The authors discuss the properties of the FLR as a scatterometer. The ability of the FLR to measure radar cross sections, taking into account the effects of the focused-beam antenna, is determined by modeling and measurements. A family of calibration curves is obtained and will be incorporated into the radar signal processing software. Backscatter measurements of two disks with radii of 2.8 and 5.0 cm were made with FLR at ranges from 1 to 6 m. The measurements agree very favorably with the theoretical predictions.>