Polarization grid is a frequency selective surface with broadband characteristics, which is composed of a group of equally spaced metal wires. When the polarization direction of the incident electromagnetic wave is parallel to the direction of the polarization grid wire, the electromagnetic wave is fully reflected.

When the polarization direction of the incident electromagnetic wave is perpendicular to the direction of the polarization grid wire, the electromagnetic wave can be fully transmitted. Therefore, polarization grid can be used as a polarization filter and is widely used in the field of microwave remote sensing.

Polarization grids can be used as polarization filters and are widely used in the field of microwave remote sensing. Polarization grids are a very important basic device in millimeter wave terahertz quasi-optical links. In passive remote sensing, they are mainly used for polarization separation of electromagnetic waves.