A novel impedance matching method of helix antenna

A novel impedance matching method of a helix antenna is proposed in this paper. The conventional impedance matching of a helix antenna is based on the method of adjusting the thickness of the substrate and making a tapered transition between the helix antenna and the coaxial cable. However, these methods are not easy to be controlled. This paper designed an improved impedance matching method, using double-layer metal structure. By changing the dimension of the top metal, the input impedance of the helix antenna is easy to be controlled. Thus the design process can be greatly simplified. In order to validate its practicability, a helix antenna working at 5.8GHz is fabricated. The effect of several design parameters, including turn numbers, pitch, helix radius, and input impedance are studied, especially the effect of ground plane. Finally, a good agreement between the simulated and measured results is observed.