A Novel Compact Triple Bandpass Filter Using Loaded Microstrip Resonator with Interdigital Capacitor

In this paper,a compact triple-narrowband bandpass filter is designed and proposed using microstrip resonators in combination with interdigital capacitor . The proposed triple-band BPF consists of two half-wave resonators in combination with a simple anti-parallel coupled lines which realizes a triple-band BPF with a size reduction about 42% in comparison with the conventional one. To demonstrate three bands, three different coupling paths are realized between two resonators.To improve the insertion loss of the filter, the proposed structure is combined with an interdigital capacitor. Additionally, transmission zeroes of the proposed structure guarantee the sharpness the skirts of scattering parameters of triple-band BPF. The frequency response of the filter is simulated using an EM simulation tool and then measured where a good agreement between them is reported.

Keywords:

Anti-parallel coupled lines , half-wave resonator , interdigital capacitor , triple-narrowband bandpass filter