Reconfigurable Bandpass Filter with Variable Bandwidth at 5.8 GHz Using a Capacitive Gap Variation Technique

A reconfigurable bandpass filter that consists of capacitive coupled resonators has been designed with the capability to switch between two distinct bandwidths while keeping a fixed center frequency of 5.8 GHz. This filter can be adapted between a narrowband state with a 4% bandwidth and a wideband state with a 10% bandwidth. This filter achieves a passband reconfiguration ratio greater than 2:1 using only 2 resonators. The design presented here introduces a capacitive gap variation technique for tunable bandpass filters offering great adaptability and full control over parameters such as overall quality factor, center frequency, passband ripple, and bandwidth. Measurements are included demonstrating this technique and verifying the implementation of the filter.