Design of the 4-element rectangle radial line helical array antenna

Radial line helical array antenna is a novel antenna which realizes the directional radiation of circularly polarized high power microwave. This paper put forward a rectangular radial line helical array antenna (subarray), which uses short helical antenna as its radiation element, each helix is excited by the energy coupled by a probe from a radial line waveguide, especially it can be simply assembled a number of subarray to a high gain array antenna. In this paper, a L-shaped coupling probe is advanced, which are suited to high power application. The 4-element helices and probes are arranged on the upper plate of the radial line waveguide to form a rectangular antenna array with uniform square lattice. The paper presents the fundamental conception of operation, derives pertinent design and performance, and gives the numerical simulation result on antenna prototype. In addition, numerical simulation result shows that: the subarray is easy to achieve uniform amplitude and phase distributions. At center frequency, the antenna gain is about 12.57 dB with axial ratio 1.55. In the range of 3.6 GHz to 4.0 GHz, the antenna gain and aperture efficiency are over 11.6 dB and 90%, antenna axial ratio and reflectance are below 1.55 and 0.2, respectively.