Generalized Chebyshev filter integrated design method based on conformal transformation

Abstract

The invention relates to a generalized Chebyshev filter integrated design method based on conformal transformation. The method comprises the steps of Step 1, constructing a characteristic function in a z region; Step 2, deriving polynomials from the characteristic function according to indexes; Step 3, converting polynomials and scattering parameters formed by the polynomials into admittance parameters; Step 4, conducting partial fraction expansion on the admittance parameters, and contrasting the admittance parameters with corresponding admittance parameters in a transverse equivalent circuit, so that corresponding parameters such as coupling coefficients and resonant frequencies can be determined, and a network matrix which is represented in a global resonance mode can be obtained; and Step 5, converting the network matrix which is represented in the global resonance mode into a desired sparse topological structure through multiply transformation, rotation transformation and the like. Compared with the prior art, the method has the advantages that generalized Chebyshev band-pass filters of any bandwidth can be synthesized, transmission zero can be located at any limited frequency or an infinity position, and the method is simple and easy to implement.

Description

technical field [0001] The invention relates to the technical field of filters in communication technology, in particular to a method for comprehensively designing generalized Chebyshev band-pass, band-stop and low-pass filters with arbitrary bandwidth. Background technique [0002] One of the key devices in the RF / microwave filter communication system. Modern communication systems usually require filters to have good frequency selectivity and other characteristics. If coupling is introduced between non-adjacent resonators, it is possible to generate transmission zeros located at finite frequencies or at infinity, thereby improving the frequency selectivity of the filter or suppressing unwanted harmonics. For this type of filter, that is, with transmission zeros located at finite frequencies or at infinity, they are often synthesized by generalized Chebyshev filter functions. The traditional approach starts with a low-pass prototype, which is converted to a band-pass filte...

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Problems solved by technology

[0003] The purpose of the present invention is to overcome the deficiencies and defects existing in the prior art, to solve the shortcomings of the existing generalized Chebyshev bandpass filter synthesis design methods such as narrow-band approximation restrictions or complicated processes, and propose a generalized Chebyshev based on conformal transformation A Chebyshev filter synthesis design method that can be used to extract the coupling matrix of a bandpass filter with arbitrary bandwidth and transmission zeros located at arbitrary frequencies

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