A Miniaturized Interdigital Bandpass Filter for Intentional Electromagnetic Interference Applications

We propose a compact bandpass filter over 0.52-2.07 GHz at the receiver front-end of an intentional electromagnetic interference detection system. We design the filter using five microstrip stubs arranged in interdigital configuration along with a dumbbell shaped defected ground structure. We design the proposed filter on FR4 substrate with a relative permittivity of 4.4 and a thickness of 1.6 mm. We obtain a 3dB fractional bandwidth of 119.96%. The proposed filter exhibits a return loss >12 dB, an insertion loss ≈0.922 dB and a flat group delay over the entire bandwidth. Also, the proposed filter is compact and occupies an area of 3.55 × 1.557 cm2. As compared to the state-of-the-art designs, the proposed bandpass filter is highly miniaturized, easy to fabricate and exhibits good performance.