A reconfiguralbe hybrid coupler circuit for agile polarisation antenna

In this paper, we present a reconfigurable hybrid coupler suitable to feed any printed radiating element for full polarisation agility. The whole structure can alternatively radiate electromagnetic waves with orthogonal linear, right or left hand circular polarisation (CP) upon changing the state of the quasi-lumped hybrid coupler. A prototype is realized with a 0.762- mm-thick upper layer substrate and a 0.130-mm-thick feed layer substrate, both of the same dielectric material with a relative permittivity of epsiv_r=2.22. Simulated and measured matching, insertion loss, axial ratio, gain and radiation pattern are presented.