UWB stripline coupler with low loss and ripple

Abstract

An asymmetric multi-section ultra-wide band stripline coupler with two coupled parallel stripline is proposed. The primary features of the coupler include operating frequency from 2 GHz to 18 GHz to cover S, C, X, Ka and Ku bands; coupling coefficient below -18 dB; return loss of -20 dB for all the ports; minimum directivity of 25 dB; small size and low losses, which make it appropriate for applications, where the available space is limited. The coupler parameter values are obtained after a two step optimization process using i) a genetic algorithm with Matlab; and, ii) a particle swarm algorithm with HFSS software. The whole structure is simulated, fabricated and measured. There is an excellent agreement between measured and simulated results.

Design of wideband directional coupler based on secondary stage coupled structure

“…In previous designs, directional coupler was designed using multilayer structures, [3][4][5][6] which provide tight broadside coupling across wideband. Furthermore, parallel coupledline couplers [7][8][9][10][11][12][13] are widely utilized in many wireless and microwave applications. Although it has the characteristics of wideband and strong coupling, the coupler is difficult to achieve the desired performance.…”