Design of dual-mode tunable filter surrounded by an electrical wall to obtain shielding effect

This paper presents an electronically tunable filter implementation based on microstrip patch resonator surrounded by an electrical wall to reduce insertion loss of the filter. The dualmode tunable bandpass filter is realized using varactor diode elements. The passband of the filter covers different six states (responses) ranging from 2.0GHz to 2.53GHz. The filter exhibits an insertion loss of 1.68–3.90 dB across the whole tuning range. The designed filter is fabricated on a single-layer using PCB technologies. The simulated and measured results are presented, which show very good agreement. The proposed filter shows promising application for the design of continuously tunable bandpass filters, because it presents a compact layout and low insertion loss.