The Research And Design Of Wideband And Dualband Directional Couplers For Mobile Communications

As the key components of the communication system, the design of the directional couplers is always the research hotpoint of microwave devices. With the rapid development of mobile communications and wireless communications in recent years, especially the TD-LTE commercial license and FDD-LTE test license being issued in China, the broadband or multiband directional couplers are required intensely.Based on the above background, a broad-frequency-band directional coupler and two dual-frequency-band directional couplers have been designed in this thesis. In broad-frequency-band directional coupler, the matching network and defected ground structure(DGS) have been introduced to broaden the frequency band and improve the performance of the directional coupler. And then in order to achieve the dual-frequency-band directional couplers, the open stub line and simplified composite right/left handed(CRLH) structure have been applied to conventional broad-side-coupled directional coupler. The coupling factor and isolation of the directional couplers designed in this thesis meet the requirements and the frequency bands almost cover the bandwidths of domestic GSM, 3G and 4G mobile communication system.The broad-frequency-band directional coupler and the dual-frequency-band directional couplers designed in the thesis have good performance and practicability, and they can be used in the system of mobile communications and wireless communications. The analysis and design process in the thesis can be used for other broad-frequency-band and multi-frequency-band directional couplers design.