Features:Circularly polarized antenna with its big advantages in the wirelessfield plays an important role. Linearly polarized wave transmissionenvironment is easy to cause deflection of the polarization decay, thecircularly polarized wave encounters an obstacle in the reversedirection, because of the direct wave and the reflected wave havepolarization isolation, the circularly polarized wave has a strongability of anti-interference ability and anti-fog.Specifications:Copper Circular Bottom Screw: 16DBicopper round spiral: 14DBiPlastic Square Bottom Spiral: 12DBiDirectivity: DirectionalBest for: For video receiver.Package list:1 * 5.8g L monopole antenna helical antenna