Research on a circularly-polarized spiral antenna with a simple dielectric lens

This paper investigates a wide beam circularly polarized Archimedean spiral antenna (ARSA) scheme. In order to broaden the pattern width of the ARSA, this paper loads a dielectric lens structure above the traditional Archimedes spiral antenna, which changes the phase distribution of the antenna aperture field, and thus widens the beam width. The designed dielectric lens consists of a concave dielectric lens and a stacked ring-shaped absorbing material. By adjusting the vertical distance between the dielectric lens and the ARSA, as well as the size parameters of the dielectric lens, the radiation pattern at a certain frequency point can be broadened. The designed ARSA is a printed dual arm structure that uses a cylindrical metal back cavity to achieve a unidirectional radiation pattern. Absorbing materials are loaded at the bottom of the metal back cavity to improve the pattern performance. An antenna structure operating at 2.365GHz was designed using full wave electromagnetic simulation technology. The simulation results showed that at the operating frequency point, the gain of the antenna was about 6.243dBi, and the beam width was extended. The axial ratio of the antenna in the normal direction was less than 3dB within the range of 2.365GHz to 2.8GHz. The research results of this paper provide a technical reference for the design of wide beam antennas.