Ka-Band Quasi-Optical Measurements Using Focused Gaussian Beams

This paper describes the use of focused Gaussian beams in making quasi-optical measurements at Ka-band. Measurement results for a known standard are presented to validate the measurement technique. Measurement are presented both for the case in which the beam waist is smaller than the quasi-optical array under test and in which the beam waist is slightly larger than the array. The measurements are compared with simulations of infinite arrays illuminated by plane waves. Good agreement can be found between measurement and simulation, provided appropriate calibrations are performed and certain precautions observed. This paper describes a newly developed calibration technique that can be applied when the size of the array under test is comparable to or slightly smaller than the beam waist.