Analysis of Planar Microstrip Circuits Using Three-Dimensional Transmission Line Matrix Method

The frequency-dependent characteristics of microstrip planar circuits have been previously analyzed using several full-wave approaches. All those methods directly give characteristic of the circuits frequency by frequency. Computation time becomes important if these planar circuits have to be studied over a very large bandwidth. The transmission line matrix (TLM) method presented in this paper is another independent approach for obtaining the frequency-domain results for microwave circuits through time-domain results, followed by Fourier transform. The advantage of this method is obtaining characteristics versus frequency over the whole band with a single simulation. The method is shown to be an efficient tool for modeling microstrip planar circuits as well as rectangular microstrip antennas and filters. The frequency characteristics calculated with the 3D-TLM method show excellent agreement with measured values and results obtained by other methods.