The Multimode Diplexer Technology,

Microwave Waveguide Diplexer works in the front-end of RF transceiver. It is composed of two different microwave waveguide filters: TX filter and the RX filter. When the transceiver receives signals, signals are passed through RX filter while the TX filter's signals are suppressed. The case is contrary when the transceiver transmits signals. The diplexer in this thesis is a dual-mode waveguide diplexer, of which filters are all dual-mode waveguide filters. We first discuss the basis theory of dual-mode waveguide filter and its design method in this thesis. Then we designed two waveguide diplexers according to the method of filter designing. The three main characteristics of dual-mode waveguide diplexer in this thesis are presented: 1, a new dual-mode technology is used based on the original dual-mode resonator to make process easier; 2. the shape of dual-mode diplexers can be flexibly changed to meet different design requirements because the location of dual-mode resonators' input and output can be flexibly changed 3, By adding a low-pass filter device in the TX filter and RX filter. The problem that the dual-mode diplexer's spurious band is too close can be solved effectively.This thesis describes a 14GHz satellite communication dual-mode filter's designing and test results. The filter uses a new dual-mode technology to reduce the difficulty and cost of processing, and has better stop-band selectivity as well as a very small insertion loss. Basis on this, we designed a 13GHz point to point communication dual-duplexer. And the results show that point to point communication dual-duplexer also has a very good performance.In this thesis, the study of suppression of spurious band for dual-mode duplexer has been done, in which the low-pass filter is added at the two RF ports to suppress the spurious band. Basis on this study we have designed a 15GHz point to point communication dual duplexer which can suppress the spurious band, and the test results show better performance.