A novel low-profile circularly polarized antenna with low angle coverage

In this work, we present the design of a low-profile circularly polarized antenna with a wide beam-width for low-angle coverage. The antenna consists of two parts: a dielectrically loaded short circuited quadrifilar helical antenna locates at the center, with its four ports terminated by 58 ohm impedance each. Additionally, four monopoles with 90° phase progression are placed around the helix, and sections of Archimedean spiral are used to topload the monopoles. The designed antenna has a peak gain of approximately 3dB and its 3dB beam width is 150°. The axial ratio of the antenna is less than 3 in the entire upper hemisphere over a wide frequency band, and its bandwidth is 18%.