Interdigital Microstrip Circuit Parameters Using Empirical Formulas and Simplified Model

Empirical formulas are given for single and coupled microstrips, directly giving propagation mode admittances and phase velocities to be used in simplified expressions for the admittance parameters for the 2N-port network N coupled strips form, thus forming the basis for fast, practical and accurate methods for both analysis and synthesis of interdigital microstrip circuits. Calculated and measured results are presented for two interdigital bandpass filters, synthesized as Chebyshev filters.