FRESNEL-ZONE PLATE AIDS LOW-COST DOPPLER DESIGN.

Design of a low-cost Doppler homodyne radar is outlined. It employs Gunn diode which acts as the transmitter, the local oscillator, and the mixer. Fresnel half-period zones are cut from a plastic sheet. The radiated field is built by superimposing all of the wavelets. The plastic zone plates can be mass produced using plastic molding methods, and are used as quasi-optical lenses for the collimation and focusing of the radar beam.