Novel In-line Beeline Compact Microstrip Resonant Cell

Two novel beeline compact microstrip resonant cells, entitled BCMRCs, are proposed. Their photonic bandgap and slow-wave effect are evaluated. These compact configurations present super broad stopband and improved slow-wave characteristics. Two lowpass filters, consisting of three such BCMRCs connected in series, are designed, fabricated and tested. Both lowpass filters show above 128% (above -10dB) bandwidth from 6.6 to 30.1GHz and from 6 to 28GHz, respectively, which is the widest in all CMRC structures. The filters have the advantages of low insertion loss (<1.2dB) in the passband, sharp, high and wide rejection in the stopband and compact size. Good agreement between experimental and simulated results is achieved