Characteristics of a quadrifilar helical antenna with a ground plane in dual-frequency bands

摘要

The simple structure quadrifilar helical antenna with a ground plane which has parasitic elements placed in middle of fed elements on the same circumference was investigated in dual-frequency bands. As the results by using the moment method, the dual-frequency band operation is realized if the length of fed elements are 3/4X at the low frequency, and the parasitic elements are a little shorter than 3/4X at the high one. The prototype antenna based on these results for GPS applications has good characteristics in terms of return loss, radiation patterns and axial ratio, similar to the simulation.