Design of an ultra-compact dual-band bandpass filter with CRLH resonator

An ultra-compact dual-band bandpass filter (BPF) with coupled novel composite-right/left-handed (CRLH) resonators is presented. The proposed CRLH resonator is constructed by a serial interdigital capacitor and a short-ended meander line, which have the advantages of small size and more flexible resonant frequency allocation. The proposed filter has been simulated, fabricated and measured. The dual-band BPF achieves the fractional bandwidth approximately 12.7% at the first center frequency 0.95 GHz and 9.2% at the second center frequency 3.12GHz, the return loss is greater than 10 dB in passband, with an ultra-compact size as small as 0.11λg×0.059λg, λg is the guided wavelength at the center frequency of the first passband.