Proceedings of the 46th European Microwave Conference Multi-Coupled Resonator Microwave Diplexer with High Isolation Augustine O. Nwajana, Kenneth S. K. Yeo Department of Electrical and Electronic Engineering University of East London London, UK
[email protected] Abstract—A microwave diplexer achieved by coupling a dual- and dual-band filter (DBF) design [7], engineers can achieve band bandpass filter onto two single-bands (transmit, Tx and diplexers purely based on existing formulations rather than receive, Rx) bandpass filters is presented. This design eliminates developing complex optimisation algorithm to achieve the the need for employing external junctions in diplexer design, as same function. Also, since the resultant diplexer in this paper is opposed to the conventional design approach which requires formed by coupling a section of the BPF resonators, onto a th separate junctions for energy distribution. A 10-pole (10 order) section of the DBF resonators, a reduced sized diplexer is diplexer has been successfully designed, simulated, fabricated achieved. This is because the energy distributing resonators and measured. The diplexer is composed of 2 poles from the dual- (that is, the two DBF resonators), contribute one resonant pole band filter, 4 poles from the Tx bandpass filter, and the to the diplexer Tx channel and one resonant pole to the diplexer remaining 4 poles from the Rx bandpass filter. The design was implemented using asynchronously tuned microstrip square Rx channel. Therefore, the large size issue with the open-loop resonators. The simulation and measurement results conventional diplexer design can be avoided, as external show that an isolation of 50 dB is achieved between the diplexer junctions (or external/common resonator) are not required.