Characteristics of a Broadband Microwave Corrugated Feed: A Comparison Between Theory and Experiment

It has been shown by Thomas 1 that under certain conditions the field over the aperture of a corrugated feed is virtually constant over a very wide frequency range. For this behaviour to occur, the radius a of the aperture must be much larger than a wavelength, i.e., (1) and furthermore, the aperture must be illuminated by a single mode. If both conditions are satisfied, we can show that the field distribution is essentially independent of the surface reactance of the corrugated horn wall, Xs, and, as a consequence, it is little affected by the variation of X s with frequency. This result is very important, for it implies that it 869 a(o) - 0.629 cm b(o) =1.161 cm a(z 2 ) " 3.144 cm b(z 2 ) - a ( z 2 ) ~ X / 4 AT 22.9 GHz Z| · 45.7 cm z 2 · 78.7 cm Fig. 1--Dimensions of the corrugated horn.