A Simple Method to Estimate the Propagation Constant of Microstrip line and its Application on the Design of Microstrip Leaky Wave Antennas

A simple and efficient method to estimate the propagation constant of microstrip lines is proposed in this paper. By making use of the structural symmetry of microstrip lines, the insertion of PEC (PMC) symmetry walls can force the microstrip line to operate at a single 1st higher order (quasi TEM) mode. The corresponding complex propagation constant can be estimated from the S parameters using the multi-line method with the aid of full-wave simulators. The method can be a valuable tool for the accurate design of microstrip leaky wave antennas.