Dual-band Bandpass Double Ground Plane Coaxial Resonators and Filters

This contribution proposes a novel double ground plane coaxial resonator that allows to utilize two independent coaxial cavity modes in reduced physical volume. This configuration of compact high performance filters is an enabler for multi-band transmitter architectures using modern Radio Frequency data convertors (RFDAC). The benefit of the proposed approach is the ease of design and the design flexibility. The filters proposed, provide the ability to control the frequency, the bandwidth and the introduction of transmission zeroes (TZs) separately for each band. A number of designs are presented to demonstrate the operation principle and the performance characteristics of the proposed filters. A 2x4 pole filter has been manufactured and tested with very good obtained results.