Design of a Dual Polarized mmWave Horn Antenna Using Decoupled Microstrip Line Feeder

In this study, a dual polarized horn antenna (DPHA) with a novel feeding system was designed at W band for millimeter wave receivers. The DPHA consists of the printed circuit board (PCB feeding system and back side short cavity, which closes the rear of the wave guide and a pyramid horn in the direction of radiation. The PCB feeding system has two orthogonally positioned microstrip line feeder elements with 50 Ohm microstrip transmission line (MTL) and symmetrical square patches. There is enough space in DPHA for additional electronic circuits following the feeding system, such as LNA and mixer. Moreover, various parasitic strip line structure such as monopole, T shape, Y shape, short circuit and neutralization line were then added between the square patches so as to further increase the isolation between the feeding ports. The best isolation level was thus achieved by using the monopole structure without resulting in a gain loss. The DPHA was therefore designed with higher than 20dBi gain and a level of 15dB isolation as dual polarization between 80GHz and 100GHz. The DPHA can be used in millimeter wave polarimetric imaging systems and similar applications.