Switchable tri-band bandpass filter with wide stopband

A compact switchable microstrip tri-band bandpass filter with a wide stopband is presented in this paper. Thanks to the low loading effect of distributed coupling technique, three channels can be obtained without the conventional complicated matching network. Three passbands can be turned on and off independently by using p-i-n diodes. To validate this design concept, theory as well as experiment is presented and compared in this paper.