Akademik Veri Yönetim Sistemi
5th International 19 May Innovative Scientific Approaches Congress, Samsun, Türkiye, 19 Mayıs 2021, ss.198-210
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.