Research On The Design Techniques Of 6-18GHz Ultra-broadband Coupler

Directional couplers, as a kind of microwave signal samplers, find wide application in microwave networks and systems. They perform a variety of functions, such as splitting and combining power, sampling power from sources for level control, separating incident and reflected signals in network analyzers, feeding network for antennas. All directional couplers have the special property of coupling energy from a specific direction into a coupled port. Today’s military and civilian communications develop in the direction of higher frequency and the ultra-broadband directional coupler of high performance has been one of research priorities.The main task of this thesis is to design the directional coupler for monitoring the operating state of the small signal gain adjustable solid-state power amplifier in the automatic test system of traveling wave tube(TWT).This paper will elaborate the design methods of nonuniform and multisection directional couplers based on coupled transmissions, combing with the theory of couplers. The work of this thesis is divided as the following aspects:1.The basic concepts and analysis methods of directional coupler, including odd-even mode analysis and the applications of Matlab in the microwave network analysis are introduced.2.The analytical and synthetical formulas of some common coupled transmission lines are systematically summarized. MATLAB programs for the analysis and synthesis of coupled transmission are developed, which lays the foundation for the design of the non-uniform coupler.3.The ultra-broadband non-uniform coupled-line directional coupler is studied. As examples, two non- uniform directional couplers covering the frequency range from 6 to 18 GHz with 20 d B coupling are designed by employing edge-coupled striplines and edge-coupled microstrip lines, respectively.4.The ultra-broadband multisection uniform coupled- line directional coupler is studied. As examples, two directional couplers offering 3 d B and 20 dB coupling over an ultra-broad frequency band from 6 to 18 GHz are designed by employing offset coupled striplines and slot-coupled microstrip lines, respectively.The feasibility of the design methods of ultra-wideband directional coupler is verified by four examples in detail. This paper has obtained the periodic achievements and it provides a certain reference for the subsequent design of ultra-broadband directional coupler...