First reflectivity results with a portable 92 GHz radar

A portable, battery-powered 92 GHz pulse radar has been constructed for field measuring purposes. The device utilizes two Gunn oscillators operating at a frequency difference suitable for downconversion. It has 20 mW of transmit power, a dynamic range of 50 dB and the antenna gain is 40 dBi. The pulse width is 100 ns and the radar includes a fast sample and hold module suitable for long term reflectivity recordings at selected distance. Total equipment weight is 2 kg without 12 V/5 Ah battery. Examples of first measurements are shown. RCS calibration uncertainty at 50 percent level is ±1.5 dB. Observed tree reflectivities partly exceed those extrapolated from previously published results giving typical levels of 0 to 5 dB(m²/m²) both for coniferous and deciduous samples and a data spread of ±6 dB.