Radiation Fields of Corrugated Horn Antenna over Lossy Dielectric Half-Space


Mohammed Musa D. S. , Daşbaşı R. , Polat A. B.

5th International 19 May Innovative Scientific Approaches Congress, Samsun, Turkey, 19 May 2021, pp.198-210

  • Publication Type: Conference Paper / Full Text
  • City: Samsun
  • Country: Turkey
  • Page Numbers: pp.198-210

Abstract

Conical horn is an aperture type antenna having a cone-shaped metallic structure and fed by a cylindrical waveguide. These antennas are used in complex systems such as cellular communication networks, satellite communication and radar systems, as well as in laboratory applications such as gain and pattern measurements. Conical horn antenna provides high performance features such as wide bandwidth, high gain, narrow beamwidth, and dual polarization. In addition, it has simple mechanical structure which is suitable for manufacturing. Corrugated conical horn (CCH) antennas are obtained by periodically corrugating the inner wall of the cone of conical horn antenna approximately by lambda/4. These corrugations bring along additional performance improvements like symmetry in the radiation pattern, lower side and back lobes. 

Radiation fields of horn antennas in free space are obtained by expressing the electromagnetic fields by equivalent electric and magnetic surface currents and calculating surface integrals under far field approximation. On the other hand, analytical far field expressions of such antennas on a lossy dielectric half-space cannot be obtained explicitly in the same way.


In this work, analytical radiation fields of CCH antennas on a lossy dielectric half-space are presented by using the directional currents method (DCM), which was developed in 2020 by the second and third authors for pyramidal and conical horn antennas. As required by DCM, the radiation fields of an aperture antenna in a non-homogeneous medium is matched analytically with the radiation fields of cross polarized electric and magnetic dipole antennas situated on the aperture surface. To do so, first the directionality feature is given to the currents on the dipole antennas in a way as to meet the free space radiation patterns of the CCH antenna exactly. Then, the radiation field expressions of dipole antennas carrying constant phasor currents over the lossy dielectric half-space are multiplied by directional currents. This reads analytical expressions of the radiation fields of the CCH antenna in the same medium, which apply under high contrast approximation for the air-dielectric interface.

Obtained analytical expressions are compared with the simulations of a commercial electromagnetics software and the relative performance of CCH antennas over standard conical antennas over a lossy dielectric half-space is discussed. These results are encouraging for manufacturing the CCH antenna and performing experimental tests within the scope of surface wave radar studies at Radar Research Laboratory of Yıldız Technical University.