Compact filter using coupled metamaterial mushroom resonators with corner vias

In this paper, it is shown that the application of metamaterial resonators to the design of planar microwave filters provides a high level of miniaturization. Specifically, mushroom structure is used to synthesize microwave filters using the coupling coefficient approach. It is also shown that by changing the position of the metallic via in the mushroom cell from its center to corner, the resonance moves towards lower frequencies. This allows an easy structure size reduction which is critical in many applications. The magnetic and electric nature of the coupling coefficient is analyzed in detail. Finally, a bandpass filter operative at 2.46 GHz is simulated in ADS Momentum and also fabricated. The measured results show that the filter has an insertion loss less than 1.5 dB and bandwidth of 400 MHz with 15 dB rejection at 2.46 GHz. The dimensions of the experimental filter are 2.4 mm × 3.0 mm × 1.27 mm.