ANALYSIS OF GEOMETRY CHANGES TO THE ISOLATION ON THE MICROSTRIP BRANCHLINE COUPLER

Abstract

In this research, Microstrip Branch line Coupler based simulation will be carried out with each input
and output impedance of 50Ω. where has a different shape (geometry) but has the same dimensions,
one is H shape junction and the other is J shape junction. Coupler is a passive multiport device that
each port can be the entry point or exit point of the wave. The material used is Epoxy, and works at a
frequency of 3.0 Ghz, and can be applied to the duplexer used in pulse radar antenna systems. First,
using the initial parameters from the calculation results there was a shift in the working frequency of
the desired VSWR value ≤ 1.5 and the desired coupling factor of -3 dB. For coupler simulation, CST
2019 software is used. The most influential coupler simulation results are the isolation value for H
shape junction S14 = -44.79 dB and J shape junction -52,296 dB. Other parameters J Junction Return
loss -30,725 dB, insertion loss -3.5926 dB, Factor coupling -3.42 dB. While the value of vswr is = 1.
036, for the H junction value can be seen in the table.