Compact Dual-Frequency Microstrip Branch-Line Coupler Using Artificial Transmission Lines

This paper describes the analysis of a compact dual-frequency microstrip coupler design. The proposed design has significantly smaller dimensions compared to the conventional design. The method of size reduction consists in using artificial transmission lines instead of quarter-wave transmission lines. The artificial transmission lines have similar characteristics to those of the substituted transmission line segments. Numerical simulation of the microstrip device, which is able to operate at two different frequencies of 820 and 2000 MHz, was performed using AWR DE software. The surface area of the obtained structure is 71.6% less that of conventional design structure.