Waveguide Dual-mode Filter Design

In recent years,along with the high development of wireless communication in business,the miniaturization of electron equipment becomes a very important problem. Almost all intermediate frequency and base band in lower frequency circuits,adopt large-scale integrate circuit include filter,so the miniaturization of these circuits upgrades along with the development of semiconductor.In aspect of microwave,along with the development of single chip microwave integrate circuit,microwave active circuits,such as amplifier,modern,become more and more miniaturized,but there are deficiency in microwave filter and oscillators' microwave circuits' miniaturization. So,developing high performance and miniaturized microwave filter is a hot topic in nowadays.In this thesis,the main research contents are the principles and realization,first,the basic theory on the microwave filters,and the responses of the chebyshev and elliptic function are introduced,then analyse the occur of the transmition zeros and the synthesis of coupling matrix.Excitated degenerate modes in the circular waveguide or the square waveguide and produced the coupling between the degenerate modes with the coupling screws or the coupling square-corner-cut.In this thesis,based the relation of the external quality factor and the phase or the group delay,a project of finding the size of external coupling hole with the means of extracting the external quality factor are proposed out. We can obtain the approximate sizes of the cross-coupling-iris and evanescent mode rectangular waveguide by calculating with the small-diffraction theory.Finally,we can get more accurater size of the filters by optimizing the filter's parameters.