A wideband E-plane crossover coupler for terahertz applications

In this paper, a new approach to design terahertz (THz) E-plane crossover coupler is reported. By cascading two symmetrical septum polarizers, a simple structure with wide operating bandwidth and high isolation performance is achieved. The working principle is explained by operating waveguide modes. To simplify the optimization process, the scattering matrix (S-matrix) of the crossover is calculated. Two prototypes loaded and unloaded electromagnetic band gap (EBG) are fabricated and measured. The electrical contact problem at assembly plane is eliminated by the prototype loaded EBG. A measured bandwidth of 17.3% from 92.5 to 110 GHz for reflection and isolation coefficients < −15 dB and transmission coefficient > −2 dB is achieved.