Design of microstrip interdigital bandpass filter with suppression of spurious responses for L-band wireless communication applications

摘要

In the present paper, a compact L-band microstrip interdigital bandpass filter (BPF) with spurlines is designed. In the proposed microstrip interdigital BPF, spurious responses are suppressed and stopband attenuation is better than ???14 dB everywhere upto 8 GHz excepting that near centre frequency of 4.87 GHz. The 3-dB bandwidth of the proposed BPF is 970 MHz (0.99 ??? 1.96 GHz) with a centre frequency of 1.475 GHz. The insertion loss value of the proposed BPF varies from 0.16 dB to 0.61 dB over the frequency range of 1.04 ??? 1.91 GHz. In the desired 3-dB passband, group delay is better than 2.8 ns. The proposed BPF is suitable for the application of satellite navigation like global positioning system carriers which are in the L band, centered at 1176.45 MHz (L5), 1227.60 MHz (L2), 1381.05 MHz (L3), and 1575.42 MHz (L1) frequencies, amateur radio and digital audio broadcasting.