A compact customizable tunable EBG filter

Abstract

A novel design for compact customizable tunable EBG (Electromagnetic Bandgap) filter is proposed. The tunable filter is implemented in RO4350 substrate using PCB (Printed Circuit Board) process with surface mounted solid-state varactors and lumped capacitors. Its frequency is tuned by adjusting applied voltages of the varactors. The filter is unique that it is capable to be tuned in customizable specified frequency range by selecting the lumped capacitors. The simulated and measured results of the proposed filter are found to be in good agreement. It is demonstrated that a two-pole filter with size of 3.20 × 3.90 × 1.52 mm³ in PCB achieving performance of a tuning range of 5.3–6.3 GHz with a 1-dB fractional bandwidth below 6.35% and a constant insertion loss of 4.4 dB ± 0.2 dB.