Ka‐band circularly polarised omnidirectional antenna for wide elevation coverage

Abstract

The design, development and characterisation of an inclined waveguide slot-based circularly polarised (CP) omnidirectional antenna at Ka-band frequency are described. The antenna consists of inclined slots on a circular waveguide and a coaxial feeding probe. All the radiating slots are fed by the TM 01 mode of the circular waveguide to generate the omnidirectional pattern. Inclination of slots has been used to generate circular polarisation. The designed antenna has omni coverage in the azimuthal plane and −10°to +45°coverage in the elevation plane. The antenna has been simulated on finite element method-based ANSYS high-frequency structure simulator (HFSS) EM simulator software using proper boundary conditions. The proposed antenna has the advantages of being robust, having wide coverage, being easy to fabricate (being in waveguide configuration) and is suitable for mass production. The measured axial ratio lies well below 2.8 over the horizontal plane. A voltage standing wave ratio of 2.0:1 has been achieved over the frequency band of 37.9-38.55 GHz and the minimum omni gain of the antenna is 0 dBi over the frequency band as well as over the coverage.

28 GHz Compact Omnidirectional Circularly Polarized Antenna for Device-to-Device Communications in the Future 5G Systems

“…2b. By rotating the electric dipole to be parallel to the magnetic dipole (as shown along the z-axis) and by exciting them with a 90° phase difference, OCP radiation pattern will be generated [12]- [15], [17]- [24]. This should be contrasted with the ME or other Huygens dipole antenna systems for which the maximum directivity is along the direction orthogonal to the plane containing their orthogonal dipoles.…”

“…Many investigations of OCP antennas in the microwave frequency range have been reported [12] - [24]. In general, two methods have been adopted to realize their OCP performance characteristics.…”

“…Only (to the best of our knowledge) two designs, [23] and [24], have been reported to date that realize OCP radiation characteristics in the mm-Wave band at 37 GHz and 38 GHz, respectively. The design in [23] consists of a LP omni-directional monopole radiator and a surrounding sleeve polarizer which transforms the radiated LP wave into a CP wave.…”

“…However, its size is very large both electrically and physically, i.e., its electrical and physical diameters are, respectively, 4.7 λ 0 and 38 mm, λ 0 being the free-space wavelength at 37 GHz. The design in [24] has inclined slots etched on a circular waveguide to realize the OCP radiation. However, its volume: π (7.435) 2 × 25.05 mm 3 = 2.84 λ 0 2 × 3.2 λ 0 = 9.1 λ 0 3 at 38.3 GHz, is very large; and its fabrication is not cost-effective.…”

“…The overall size of the prototype disc-shaped antenna is compact, having the dimensions: π (2.0) 2 × 1.57 mm 3 = 0.016 λ 0 3 at 28 GHz, which is more than a 200 times smaller transverse area than the reported 37 GHz system in [23] and 500 times smaller volume than the 38.3 GHz design in [24]. The paper is organized as follows.…”