Divisor de potência banda larga 1:8 com distribuição gaussiana em stripline semi-suspensa

Abstract

This Final Graduation Project presents the design of a 1:8 asymmetrical power divider, with Gaussian distribution, operating in the Wi-Fi 6 frequency range. The proposed solution is based on multiple cascaded T-junctions, implemented in semi-suspended stripline, printed on 0.15mm thick FR-4 flexible dielectric substrate (PCB-Flex). The power divider operates from 4.9 GHz to 6.6 GHz, which represents a bandwidth of 1.7 GHz and a fractional bandwidth of 29.5%. Aiming to simplify the cascading of T junctions, the ports of each junction are converted to 50 Ω through impedance transformers. Each impedance transformer is composed by three transform sections, which increases the device bandwidth and reduces the VSWR (Voltage Standing Wave Ratio). Simulation results presents return loss greater than 15 dB and VSWR lower than 1.45 in the entire operating band. The power in the output ports presents Gaussian distribution, with a maximum variation of 0.5 dB in comparison to the design goal, in all ports, for the entire bandwidth. To validate the stripline PCB-Flex solution, the first T junction, symmetrical -3 dB power divider, was prototyped. The results of the experimental measurements show consistency with the simulation results. However, due to some constructive problems, the device presented a not completely symmetrical power division between the output ports. Port 3 received power slightly above -3 dB in almost the entire band, with values around -2.7 dB, while port 2 received power slightly below -3 dB in almost the entire band, reaching approximately -3.9 dB around the 5.7 GHz. The results demonstrate the feasibility of applying the proposed splitter in the design of a 8-element antenna array. The main advantages of the proposed solution are its reduced size, no need for soldering or introduction of concentrated elements and the reduced cost, due to the use of PCB-Flex with FR-4 dielectric material.