Substrate thickness impact to branch-line coupler miniaturization for low pass filters

The present paper is devoted to influence research of the substrate material thickness on the miniaturization degree of the microstrip branch-line coupler device. The miniaturization is executed with the replacement of the ordinary microstrip line by its equivalent in the form of lower frequencies. There have been compared the numerical simulation results of the modeling of branch-line coupler structures with 1, 1.5, 2 and 2.5 mm thickness. The received results show the increase of substrate thickness with the decrease of miniaturization degree and the band of working frequencies in comparison with the standard construction.