Upper and lower bounds of 180 degrees unit element of a ridge waveguide: Calculations and measurements

The upper and lower bounds on the actual solution of any microwave structur e is of general interest. The purpose of this letter is to compare some cal culations using the mode-matching and finite-element methods, with some mea surements on a 180 degrees ridge waveguide insert between standard WR62 rec tangular waveguides. The work suggests that the MMM produces an upper bound , while the FEM places a lower bound on the measurement. (C) 2001 John Wile y & Sons, Inc.