Electromagnetic synthesis of overlap-gap-coupled microstrip filters

This paper presents a technique for electromagnetic synthesis of microstrip overlap-gap-coupled filters. The algorithm uses a rigorous analysis, which solves an electric field integral equation in the spectral domain using the method of moments, inside an outer loop that optimizes the filter dimensions. A piecewise synthesis procedure generates initial dimensions that provide a good starting point for direct electromagnetic optimization of the complete filter. Measured results for a five-section filter are shown that verify the accuracy of this design method.<>