Design of a Miniaturized Interdigital Cavity Filter

A novel miniaturized interdigital cavity filter was proposed in this article. By comprehensive technologies such as capacitance loading, cross coupling and heteromorphic resonator, the total structure size would be reduced significantly. A prototype at center frequency of 3.8 GHz with bandwidth of 900 MHz was designed. The simulation results exhibited that a transmission zero was obtained at 2.45GHz, which benefitted the performances of roll-off and high-band suppression. The insertion loss within the passband is less than 0.09dB. The overall size was only 0.25λ
0
×0.15λ
0
×0.13λ
0
, ~70% reduced to the traditional ones.