Broadband Circularly Polarized Antenna Employing Cascaded Water Dipole and Helix

ABSTRACT This article presents a compact directional circularly polarized (DCP) antenna employing cascaded water dipole and helix. It consists of five half‐wavelength water cylinders as vertical dipoles for generating vertical electric component and six half‐wavelength open helices for horizontal electric component. The dipoles and helices are connected in series and the central dipole is splitted for a differential feed. Owing to the 90° phase difference between the vertical and horizontal fields and an asymmetric distribution of the dipole radiators, a relative broadband unidirectional CP radiation is achieved by only using a single radiator with compact size. A prototype is fabricated employing 3D printing technology, reducing the difficulty of practical realization of the antenna. Measured results show that a matching bandwidth of 30% and an axial ratio bandwidth of 10.1% are achieved. This antenna features a broadband DCP radiation while having a simple, compact, and highly transparent structure, which is potentially useful for CP wireless communications.