Coaxial Cavity Symmetric Generalized Chebyshev Filter

With the frequency become more and more destinty ,The frequency divided into kinds of communication systems become more and more narrow.To decreasing the front system's attenuation for the singnal and restraining the disturb for singal .Design narrow-band,little spoilaging, high restraination in stop-band filter is necessity.Generalised chebyshev filter with transmission zeros in any-where in imaginary axis,has high rectangle coefficient,low spoliaign in band-pass,narrow-band high power-capacity is studied in domesty and overseas.Based on the theory of passive network ,gerneralised-chebyshev filtering function is made by transmission zero through recusive technique.The aim of synthesis the transfer and reflection function is to find coupling matrix .This paper gives the method to find the coupling matrix and two examples to show the progress of the synthesis.The aim of this paper is to generate the generalised chebyshev filtering transfer function polynomial and reflection function polynomial .Synthesis the transfer function polynomial and reflection function polynomial to find the coupling matrix the main works of this paper as follows:1 Generalised chebeshev filtering functioning's transfer function polynomial and reflection function polynomial is generated by transmission zeros based on the theory of passive networks.Using the computer program ,different tramission zero will give different simulated response of the filter .After finding the tramission zeros we can find the transfer function polynomials.2 Synthesis the transfer function polynomial and reflection function polynomial. One method is to use Darlindun Method to synthesis the low prototype capacitanceand inductance ,then find the coupling matrix .3 Using the synthesized matrix and HFSS software to design generalize-chebyshev filters.After finding the coupling matrix,we can find the coupling coefficient .In caoxial cavity,we use hole to realize the coefficient.In this paper ,the simulated result agree well with theory rejection and return loss.