Used In The Study And Design Of High-power Microwave Measurement Hole Coupled Directional Coupler

Directional coupler is a widely applied microwave component in the microwave system. It can be applied in the signal generator to surveillance the power and in the receiver to be a mixer. Although researches on small-aperture coupling directional coupler in China and abroad have been long lasted, greatly varied and widely ranged, and it is a mature technology, less concern has been given to directional couplers from a transverse electric mode in a circular waveguide to the fundamental mode in a rectangular waveguide and the reports related are rare.To characterize the output of high power, short pulse microwave sources, it is often necessary to couple a small fraction of the power into a subsystem to measure the frequency, pulse waveform, and peak power. Especially in gyrotron devices, this usually entails a coupler from circular waveguide to rectangular waveguide. And, because we usually use an overmoded waveguide as the main system for high power generation and transmission, not only high directivity but also wide bandwidth is required for the coupler. So it is necessary to take a systematic research on small-aperture coupling directional coupler from circular waveguide to rectangular waveguide. The dissertation values a lot not only for theory research but for practical application.Based on some issues in hand, this dissertation took a deep and systematic research on small-aperture coupling directional coupler. Firstly, the simple case, single-hole coupling, was discussed. In the case, the hole was set at the symmetrical center of waveguides. Secondly, on base of single-hole coupling, multi-hole coupling was analyzed. The methods and approaches of these cases were compared, which were equal radius distribution, binomial distribution, Chebychev distribution, on situations discussed in details. The compared and analysis of different approaches can help us to optimize the design and to get wider application.Research works of this dissertation are as follows:1.The basic theory about small-aperture directional coupler was deduced and consummated systematically. The size of directional coupler and formula of electromagnetic field were obtained. All of these give us a full design theory of small-aperture couplers. Lots of results by this research provided not only for this field but also for other correlative fields.2.The theory analysis and numerical values computation of aperture coupling was made, and the aperture coupling was simulated in HFSS. The compared results can show that the theory is reasonable.3.In multi-hole coupling, the results were analyzed with different aperture distribution, which were equal radius distribution, binomial distribution, Chebychev distribution. Some useful conclusions were made out.4.The influence on directional coupler's feature parameters by its variable dimension was researched.