Bandwidth-Reconfigurable Coaxial Bandpass Filter With Multioctave Tuning Using a Single Element

A bandwidth (BW) tunable coaxial-loaded waveguide filter is presented in this letter based on a novel concept using a single tuning element. The operation principle relies on the rotation of coaxial resonators with respect to fixed irises in order to change the inter-resonator (IR) coupling strengths that control the BW. This mechanism features multioctave tuning while maintaining a fixed operating frequency and a stable unloaded quality factor with only one rotary post. Furthermore, the filter can be switched off by using the same tuning mechanism. A prototype is manufactured and measured to verify the proposed filter. The measured results demonstrate multioctave BW tunability from 12 to 83 MHz (tuning ratio > 6.9:1), promoting the technique for multistandard communication systems and applications.