A miniaturized dual narrow-band bandpass filter using a hairpin resonator and coupled lines

A bandpass filter with dual-band response and narrow bandwidth employing coupled line-based hairpin resonator is presented in this work. The dual narrow-band bandpass filter (DNBPF) configuration contains two series-coupled lines and a hairpin resonator. Theoretical analysis based on Even and odd mode is carried out to validate the dual-frequency response of the proposed DNBPF configuration. The passbands of the designed DNBPF are centered at 1.17 GHz and 3.5 GHz, covering GPS and WiMAX applications, respectively. The full-wave simulated 3 dB bandwidths for both the passbands are 100 MHz and 140 MHz, and their fractional bandwidths are 8.54% and 4%, respectively. The proposed DNBPF occupies a footprint of
$i$
(
$j$
- guided wavelength computed at 1.17 GHz).