Miniaturised highly selective bandpass filter with very wide stopband using meander coupled lines

A compact wideband bandpass filter with a very wide stopband for terrestrial radio (TETRA) band applications is proposed. The proposed filter employs two types of resonators: one is tri‐section half wavelength stepped impedance resonator (SIR) and the other is stub‐loaded shorted ring resonator. The proposed filter has adopted SIRs and meandering technique in achieving miniaturised size. Spur‐lines and tapped feeding techniques are infused in the filter to suppress harmonics so as to achieve wide stopband. Cross‐coupling is introduced in the filter for acquiring good selectivity. This highly selective filter has a miniaturised size of 0.09 × 0.12 λ g (28 × 36.8 mm 2 ) with a wide stopband up to 8.75 f 0 ( f 0 is the centre frequency of filter) with 25 dB harmonics suppression level.