A. S. Kondratiev – Ph.D. (Eng.), Senior Research Scientist, Almaz Research and Production Association; Moscow Power Engineering Institute (National Research University)
E. A. Tarasov – Engineer, Almaz Research and Production Association
Conical horn antennas are often used as feeds in reflector antennas, collimators, as well as measuring antennas; however, standard conical horn antennas with smooth walls have non-axisymmetric radiation pattern (RP) and different coordinates of radiation centers in planes E and H, which may adversely affect characteristics of radio systems containing such antennas. Therefore, in most cases, main requirements on the shape of the RP of a conical horn antenna are the following: the axial symmetry in E- and H-planes and low energy leakage beyond the main lobe as well as clearly determined position of the phase center. There are several modifications of horn antennas satisfying these requirements.
The paper is devoted to the analysis of dual-mode conical horn antennas, namely, the Potter horn and its modification, the Skobelev horn, which contain an irregularity in the region of effective excitation of two eigenmodes of the conical region in the horn interior. Parameters of the irregularity are selected so as to form an RP with required properties. Both antennas have a near-symmetric RP and a lowered sidelobe level in the E-plane.
Numerical modeling of such antennas is performed and mechanisms of symmetrization of the RPs of these horns are analyzed. Ampli-tude and phase distributions near the end of the irregularity and in the apertures of these antennas are obtained and compared with corresponding distributions in a horn with smooth wall with dimensions of the conical part coinciding with dimensions of the corres-ponding part of analyzed horns. It has been found that field distributions near the irregularities of both horns differ from each other as well as the aperture distributions in these horns, which are tapered and near-axisymmetric. It was noted that application of circular grooves as the irregularity in such a horn could simplify the design procedure if the degree of control over the amplitude and phase distributions is sufficient to form the required shape of the amplitude and phase distribution in the horn aperture.
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