Theoretical calculation and simulation of phase center of a radial line helical array antenna

When a radial line helical array antenna is used as power source of circularly polarized waves to illuminate a reflector, it is necessary to know the location of its phase center. The phase center of a radial line helical array antenna which is stimulated with equal amplitude and phase at 9.4 GHZ is investigated through theoretical calculation and numerical simulation. The theoretical calculation, which neglects the couple effect among radiating elements, gives a preliminary estimation of the phase center of the antenna. However, while considering the couple effect, the numerical simulation results show that the array antenna has no identical phase center for two principle planes. The parameter of the helix is therefore adjusted and the uniform phase center is obtain for θ varies from -15° to 15°. This work indicates the feasibility of this radial line array antenna as the feed of reflector antenna and provides a basic method to adjust the phase center of the array.