Differential Phase Shifters Using Corrugated, Ridge, and Fin Loaded Waveguides
One means of converting the port conditions of a magic-tee into those of a 90 degrees hybrid is to introduce external sections of waveguide at the symmetrical H-plane output ports having the necessary 90 degrees phase difference. The purpose of this article is to describe a number of realizations of such differential phase shifters (DPS), including an exact synthesis procedure not requiring computer optimization. A typical design consists of a capacitively loaded waveguide for one section and an essentially inductive waveguide for the other. The latter is simply a uniform waveguide of reduced width when compared with that of the capacitive section. An example capacitive ridge DPS exhibits a maximum phase error of +/- 2 degrees over a 20% bandwidth in WR75 waveguide with a return loss of better than 40 dB and an insertion loss <0.06 dB. (C) 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 19: 561-567, 2009.
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