Expansion And Comparison Of The Bandwidth Of Microwave Systems For Pattern Recognition

Nowadays the mode discriminators based on mode-selective coupling used in microwave system almost operate in narrow band, which is inconvenient for work. But the reports about broad band mode discriminators are rare, especially for the distributions of equal radii of coupling holes and different distance between apertures. Though the distributions of equal distance and different radii of apertures can broaden band, the experiential values will be different from the theoretical values because of the limitation of the fabrication accuracy. If the radii of apertures are fixed the band of mode discriminators can be broadened by locating the distance between apertures. This kind of discriminators will have better effect in engineering. So the systemic research of the broad band mode discriminators, especially for the distributions of equal radii and different distance, is very valuable and innovative.In this dissertation, the distributions of different radii and equal radii of apertures, different distance and equal distance between apertures are studied. The emphasis is on the distribution of equal radii and different distance. By comparing with the distribution of equal distance and different radii between apertures the optimum design can be obtained. The main production and innovation of the dissertation are listed as follows:1.The theory of the mode discriminators is analysed and consummated, and the formulae for the dimensions and parameters of the discriminators with different aperture distribution are obtained.2.For the first time, the distribution of equal radii and different distance is discussed. A practical method of the apertures placement is utilized and the multihole coupling principle of the corresponding structure is investigated.3.Some coupling functions are investigated such as binomial distribution, Chebyshev distribution and risen cosine function . A series of conclusions are obtained by comparing the computation results of the distribution of equal radii and different distance with the distribution of equal distance and different radii.4.The CAD and simulation program are established.