Compact bandpass filter with quasi-elliptic response using stub loaded resonator

In this letter, a compact bandpass filter having quasi-elliptic response is proposed using short-circuited stub loaded λ/2 stepped impedance resonator (SCSL-SIR). Five transmission zeros generated helps in achieving high selectivity and improve out-of-band rejection characteristics of BPF. A compact bandpass filter having a size of 0.109λg × 0.104λg, with a 3 dB fractional bandwidth of 14% and having lower/upper stopband roll-off rates of 1.91 dB/MHz/1.44 dB/MHz is designed at 0.350 GHz for Terrestrial Trunked Radio (TETRA) band applications.