engleski

Cutoff Frequency Optimization of Ultraspherical Microstrip Filter

In this paper the ultraspherical polynomial function is converted into physically realizable filter characteristics. The obtained characteristic possesses capability to design more classes of filters based on specifications, due to the two parameters that can be chosen freely. The practical Darlington synthesis of the third order stepped-impedance microstrip filter prototype is presented while it is noted that the filter cutoff frequency needs further optimization to take into account the practical coaxial to microstrip transition. By varying the filter dimensions in simulations it was found that the realistic transition lowers the cutoff frequency by around 10%, which needs to be taken into account in the filter design.

ultraspherical polynomials ; stepped-impedance microstrip filter ; filter cutoff frequency optimization

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