INVESTIGATION OF MICROSTRIP PSEUDO-INTERDIGITAL BANDPASS-FILTERS USING A FULL-WAVE ELECTROMAGNETIC SIMULATOR

We present recent results of an investigation into the microstrip pseu do-interdigital bandpass filters using a full-wave electromagnetic (EM ) simulator. Coupling characteristics of the pseudo-interdigital reson ators are modeled and compared with the conventional coupled hairpin r esonators. It has been shown that the pseudo-interdigital resonators n ot only allow local cross-coupling, but also allow a wider range of co uplings to be realized within a compact structure. A pseudo-interdigit al bandpass filter composed of pairs of the proposed pseudo-interdigit al resonators was designed to have a 25% fraction bandwidth at 2.0 GHz . Convergence issues of the simulations of the filter are addressed. T he filter was fabricated and tested. The measured results are presente d in comparison with the simulated ones. (C) 1997 John Wiley & Sons, I nc.