Design and simulation of low pass filters for UHF based on microstrip lines

摘要

An algorithm was developed for the synthesis of the transmission line structure for filters to be designed on microstrip lines within the UHF range. In this case, the generalized algorithm optimizes a predetermined objective function, in which electrical parameters of the filter are calculated straightforward by means of recurrent equations. Optimization is carried out for a minimum out-band energy criterion. The length of the microstrip line can be computed for desired values of source impedance, load impedance and wavelength. This procedure can be extended to any geometry of microwave transmission line, as well. The above algorithm was compared to the well-known method based on the representation of the transfer function of low-pass filter through prototype structures of equivalent concentrated transmission lines. As a result of comparison, it was found that the accuracy for the generalized algorithm was higher than for the indirect representation method. The synthesized microstrip lines are to be made up of a set of conductor segments with physical parameters chosen according to the obtained values from the developed algorithms. [References: 5]