Abstract
This article presents a method to produce a highly directive circularly polarized radiation beam (gain>35 dBi) from an all-metal circularly polarized radial-line slot array (RLSA) antenna. The antenna comprises a single-layer radial TEM waveguide, fully filled with air, formed between a metal ground plate and a parallel metal slotted sheet, leading to simple, low-cost fabrication. A prototype of the new antenna having a diameter of 0.4 m or $27\lambda _{0}$ , where $\lambda _{0}$ is the free-space wavelength at the operating frequency of 20 GHz, was fabricated and tested. Its measured peak broadside directivity and measured peak realized gain are 36.3 dBic and 35.9 dBic, respectively. The total thickness of the antenna is only 6.5 mm or $0.43\lambda _{0}$ . The aperture efficiency of the prototype is 56%, total efficiency is 95.4%, and measured 3-dB axial ratio bandwidth is 4.9 GHz (22.9%). The antenna has excellent cross-polar rejection, with a measured cross-polar level of −24.4 dB in the broadside direction. This antenna has been targeted for low-cost SATCOM terminals and wireless backhauls but due to the lack of dielectrics, it may also be useful for space and high-power microwave applications.
Highlights
As a result of existing and upcoming data-hungry devices and services, there is a growing interest among satellite operators to provide broadband internet connectivity to moving platforms anywhere anytime, such as airplanes, trains, emergency and rescue vehicles, defense vehicles and long-distance buses
We present here a circularly polarized (CP)-radial-line slot array (RLSA) antenna that is made with all-metal and does not require dielectrics or any other slow-wave structure, significantly reducing the manufacturing complexity, cost and weight of the antenna
We presented and demonstrated a design methodology for all-metal dielectric-less circularly polarized radial-line slot array (RLSA) antennas
Summary
As a result of existing and upcoming data-hungry devices and services, there is a growing interest among satellite operators to provide broadband internet connectivity to moving platforms anywhere anytime, such as airplanes, trains, emergency and rescue vehicles, defense vehicles and long-distance buses. A vital component of a mobile satellite communication terminal, known as satellite-on-the-move (SOTM), is a low-profile high-gain antenna with beam steering capability [1]. A recently invented Near-Field Meta-Steering method [1] requires a low-profile, high-gain antenna with a fixed beam as the base antenna. Radial line slot array (RLSA) antennas introduced by Kelly in early 1960s [2] are known for their highly directive radiation characteristics. This naturally low-profile antenna concept was later extended by Ando and Goto in the 1980s [3]–[9]. At the centre of the cavity, there is a feeding probe to excite an outward travelling TEM wave
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