Design and experiment of a high gain axial-mode helical antenna

A high gain axial-mode helical antenna with parasitic element is proposed. A metal wafer is used as parasitic element, loaded in the front of general axial-mode helical antenna to achieve the aim of improving antenna gain. The diameter of the wafer and the distance between the wafer and the end of the helical wire, which can influence the antenna characteristics, are both simulated and optimized by CST Microwave Studio^®, a 3-dimentional full wave electromagnetic simulation software. Prototype of the proposed antenna is manufactured according to the optimal simulated results and measured in the microwave anechoic chamber. Compared with general antennas, both the simulated and measured results indicate that the helical antenna with parasitic element can boost 0.8dB in gain under the circumstance of increasing 8.3% of the antenna axial length. In addition, this antenna can achieve the band 2.1–2.7GHz in its operating bandwidth, and the maximum axial ratio is up to 1.3dB in pass-band, which is not subject to the impact of parasitic element. The proposed antenna can applied in WLAN systems.