Shortwave Four-way Power Synthesizer Design And Simulation Research

Long-distance radio emission often requires signals in radio devices to be amplified in multiple orders so as to obtain an adequate signal power prior to the transmission to antenna. Note that generally, solid state technologies have been used in modern broad-band amplifiers for power amplification. Power combination is the usual way to achieve high power in such technologies. Therefore, high power combiners are one of the key components in radio emission devices.High power combiners can be used to obtain the superposition of the outputs of a few power modules. The total output power can be up to a few or tens of kilowatts so as to meet the needs in military and civil applications. Based upon the operating principles of transmission line transformers, this thesis reports the detailed design and simulation, which includes the following four-fold studies.1) The thesis provides an introduction to the roles of power ferrites in transmission line transformers, the material requirements in high power design, and the details of design principles and approaches for the transmission line characteristic impedance of twisted pairs and coaxial cables.2) The thesis provides the detailed derivation of transmission characteristics for 1:-1 and 1:4 impedance converters and also introduces a phase compensation technique that applied to the design of ultra-broad band combiners.3) A novel short-wave 5kW four-line power converter circuit was developed in this thesis. In this circuit, the four-line combination can be realized through two merging sub-circuits. One is to lower down the impedance and the other to raise it up. Due to the minimum of merging orders and the shortest route of power propagation, all the performance specifications are excellent, namely, the operating frequency range is 2~30 MHz, insertion loss<0.2dB, SWR<1.15, isolation>26dB, phase mismatch<3o, and merged CW power not less than 5kW.4) The commercial Solidworks software was used for mechanical design and Flotherm for thermal analysis for the overheating problem in balancing resistors due to one open circuit of four lines in the combiners. One then applied the forced air-cooling for thermal design and did the thermal simulation for the worst cases of combiner operations. One also made the characterization of static parameters of combiners and experimental validation with high power inputs.The results showed that the design approaches provided in this thesis were valid, practicable and feasible. The above studies also proved the success of this research project.