Comparison Between Fully and Partially Filled Dielectric Materials on the Waveguide of Circularly Polarised Radial Line Slot Array Antennas

This paper presents an investigation on the waveguide of circularly polarised radial line slot array (RLSA) antennas to improve gain and radiation bandwidth. Two circularly polarised (CP) RLSA antennas were designed with two different waveguide configurations. In the first configuration the waveguide is fully filled with dielectric materials and in the second configuration the waveguide is partially filled with dielectric materials and rest of the waveguide is filled with air. Numerical results of these two CP-RLSA antennas with two different waveguide configurations are presented and compared. Significant improvements have been made in the 3-dB directivity bandwidth and aperture efficiency of the antenna having waveguide partially filled with dielectric material. The 3-dB directivity bandwidth was measured 6.2% and aperture efficiency increased to 55.5%. The CP-RLSA antenna has also achieved a peak directivity of 31.7 dBic and a gain of 31.2 dBic as compared to the directivity 30.1 dBic and gain 29.5 dBic, respectively achieved with the CP-RLSA antenna having waveguide fully filled with dielectric material

Low-Cost Radial Line Slot Array Antenna for Millimeter-Wave Backhaul Links

The front-end antennas with a directed narrow beam are essential to establish a robust backhaul network for 5G network. The cost and profile of the antenna are imperative due to the large number of smaller cells envisaged for a millimeter-based 5G communication network. Radial-line slot array (RLSA) antennas are suitable due to their planar and thin height profile and single feed point. A low-cost RLSA is investigated for the millimeter-wave backhaul network without using dielectric materials. The lack of dielectric substantially reduces the fabrication cost of the antenna. The RLSA is made of two metal plates where radiating slots are on a thin-plate at the top. The results predicted through numerical simulations indicate antenna can create a narrow broadside beam without any excessive grating or side lobes

Wideband Radial-Line Slot Array Antenna Technology for Near-Field Meta-Steering Systems

The paper reviews wideband radial-line slot array design and its suitability to develop wideband beam-steering antenna through near-field meta-steering (NFSM). A low-profile and highly efficient beam-steering antenna system can be realized using the wideband RLSA and pair of metasurfaces, which are placed in the near-field region of the RLSA. In NFMS systems, the base antenna remains fixed while the metasurfaces are rotated to steer the beam in both azimuth and elevation directions. The concept was first demonstrated with narrowband medium-gain antenna, and since then, it has been extended to design high-power systems, dual-band high throughout systems, and wideband steering systems

Antenna Beam Steering by Near-Field Phase Transformation: Comparison between Phase Transforming Printed Metasurfaces and Graded-Dielectric Plates

© 2019 IEEE. The antenna beam-steering technique based on near-field phase transformation yields antenna systems that have superior characteristics compared to the traditional methods including both mechanical and electronic. Some of the unique attributes associated with this technology are its totally passive nature, low height profile, and extremely simple operating mechanism. The technology has been used to develop two generations of antenna systems. The first generation was developed using multilayered printed metasurfaces (PMs) and the second generation used graded-dielectric plates (GDPs). In terms of radiation performance, the two antenna systems are nearly identical. The height profile of a GDP based antenna is about one free-space wavelength more than the height of a PM based antenna. PMs can only be manufactured in specialised facilities while with rapid advancements in materials and 3D printing, it may be possible to cheaply develop GDPs

A Low-profile and Efficient Front-End Antenna for Point-to-Point Wireless Communication Links

This paper investigates the design and performance of an efficient, medium-gain, front-end antenna of the type of radial line slot array (RLSA), for wireless communication systems. The antenna consists of two conducting metal plates forming a radial waveguide. The top plate is composed of six rings of radiating slots in a spiral pattern. A single coaxial connector is used to feed the electromagnetic energy from the bottom of the radial waveguide. The antenna has a radius of 0.15 m and operating at a frequency of 12 GHz. It was simulated using Computer Simulation Technology (CST) Microwave Studio 2019 and the results show that the antenna has an acceptable level of impedance matching in the frequency range from 11 GHz to 13 GHz, with a peak directivity of 25.6 dBi and a peak realized gain of 25 dBic at 12 GHz. Its radiation efficiency is 96% and a total efficiency is 85.3% at 12 GHz

A Beam Squinted Linearly Polarised Radial Line Slot Array Antenna with Improved Return Loss Bandwidth

This paper presents an investigation to improve the poor return loss performance of linearly polarised radial line slot array (RLSA) antenna. The problem was tackled by applying the beam squinting technique. The antenna consists of radiating surface with a circular cavity and supports outward-travelling electromagnetic waves. The antenna is excited via a rear mounted modified disk-ended dielectric coated SMA connector. The simulation results show that the return loss performance has improved significantly over the entire frequency band with a return loss bandwidth of 52.5%. The far-field result indicates that the antenna has achieved a peak directivity of 24.7 dBi at 17 GHz with a beam squinted angle of 18° and a side lobe level of -10 dB

Investigating small aperture radial line slot array antennas for medium gain communication links

This paper investigates the performance of a relatively small aperture circularly polarized (CP) radial line slot array (RLSA) antenna with medium gain for the Ku-band. The antenna is composed of two parallel metal plates which form a parallel-plate waveguide and supports rotationally symmetric transverse electromagnetic (TEM) travelling wave. The top plate consists of radiating slot elements. The slots are arrayed on the aperture in a way to produce a circularly polarised broadside beam. The antenna was designed at the central operating frequency of 11 GHz having a circular aperture with radius of 90 mm. The predicted results indicated that the return magnitude of reflection coefficient is less than -10 dB in a operating frequency band from 10.5 GHz to 11.5 GHz. The antenna has achieved a peak directivity of 22.4 dBic with a peak gain of 22.1 dBic at 11 GHz. The CP-RLSA antenna has a predicted aperture efficiency of 40%, and a total efficiency of 93% at 11 GHz

A Double Layer Circularly Polarised Radial Line Slot Array Antenna with Uniform Aperture Illumination

In this paper, we have designed and investigated a double layer circularly polarised radial line slot array (RLSA) antenna for satellite communication. The antenna is composed of twofold radial waveguide with slots acting as radiating elements on its surface. The radiating slots are arranged in a spiral pattern on the antenna aperture. Every slot has a particular length and position. The slots are oriented in a way to intercept the radial currents on the upper waveguide. The slot lengths were varied to achieve a uniform aperture distribution. The electromagnetic power is fed from center of the lower waveguide. Numerical results show that the antenna is well matched within the operating frequency range. The far-field results indicate a peak directivity of 27 dBi at 20 GHz with a good pattern quality and lower side lobe level of -27.2 dB