Detailed Analysis of a 3 dB Microstrip Hybrid Coupler

Abstract

The paper depicts a symmetric microstrip coupler designed for WiMax applications in the frequency range of 2.32 - 2.52GHz. The proposed coupler is comprised of four resonator structures attached in parallel to the ports providing lowered isolation and increased insertion loss and coupling factor. Furthermore, the presented microstrip coupler is simulated utilizing the Sonnet Suites software with the numerical approximation of the mathematical derivation of MoM (Method of Moments) for the symmetrical structure. The simulated and fabricated results show high resemblance with the data acquired after the simulation with input match being below -20dB, insertion loss and coupling factor almost -3.0 dB and isolation factor below -50dB. The approximate values of the measured design are -15.48dB, -3.86dB and -46.63dB respectively Moreover, the dielectric substrate utilized for the proposed geometry of the microstrip coupler is FR4 with ε_r=4.4 with thickness of 1. 55mm.The proposed coupler is relatively inexpensive, reliable in the provided frequency range and could be used in wireless communication applications.