The depolarization effect of microwave in multilayer plate dielectric beam combiner

Beam combiner was the key component of compound guidance hardware-in-the-loop simulation system, which was used to synthesize microwave signal and infrared signal in a common aperture. In this paper, the depolarization effect of microwave caused by beam combiner was studied, and the standard equation of linear polarization wave depolarization into elliptic polarization wave was derived. The reason of depolarization was analyzed, which was that the cross-polarization component perpendicular to the main-polarization component was generated after the microwave passed through the beam combiner. The condition to avoid depolarization was given. A polarization-insensitive beam combiner composed of three-layer dielectric working in X, Ku and K bands was designed. Its microwave transmittance was greater than 96% and the polarization angle deviation was less than 0.1.