A novel compact and highly efficient dual-polarized horn-like antenna is presented. It exploits a radiating aperture that is fed by four smaller waveguides via a quad-furcated junction. The antenna also comprises the full feed network for the feed waveguides including an integrated 4-way orthomode power divider. Design principles are described in detail and illustrated by means of an example involving an antenna with aperture size of 2.6λ0×2.6λ0 (λ0 the wavelength at the central frequency of operation) intended primarily for Geostationary Orbit (GEO) satellites. The antenna feed was designed to comply with the Additive Manufacturing rules and exhibits aperture efficiency levels close to the theoretical maximum ones over the entire transmit Ku band (10.7 -12.75 GHz), while at the same time its profile is highly compact (6.4λ0). The measured results of a prototype 3D-printed in Selective Laser Melting (SLM) verified experimentally the calculated high aperture efficiency (over 90%). The total antenna feed attains return loss > 19 dB and maximum cross-polarization isolation (XPI) > 24 dB over a bandwidth of 18%. In light of the favorable electrical performances and compact size, the proposed solution constitutes an appealing alternative to profiled (or spline) horns for satellite antenna systems used either as reflector feeds or direct radiating arrays.

The concept and development of a highly efficient pyramidal horn is described. The radiating element comprises a rectangular radiating aperture fed by two smaller flared square waveguide sections via a bifurcated H-plane surface discontinuity. For the simultaneous feeding of the 2-port radiating element, the total antenna includes a compact H-plane power divider. Properly weighted TEn0 modes (n∈N * ) are excited at the output of the two flared waveguide sections. The bifurcation is responsible for the recombination of the incoming fields. The lowdispersive modal coupling coefficients (or transmission coefficients of the bifurcation's generalized scattering matrix) between the excitation and the aperture modes enable the broadband realization of the targeted aperture modal content. The common waveguide section is responsible for the phase alignment of the aperture modes. The design method targets a pre-optimized model which approximates the amplitude of the aperture modes TEm0 (m = 1, 3, 5, …) in the order of 1/m and minimises their relative phase difference. Finally, maximum aperture efficiency can be achieved by fine tuning and with low computational complexity. Design principles are given and illustrated by means of an example involving an antenna with aperture size of about 2.8λ0×1.4λ0 (λ0 being the free-space wavelength at the central frequency of operation). The antenna exhibits aperture efficiency levels above 95% over the entire Ku-Tx band (10.7 -12.75 GHz), as well as a compact profile (4.1λ0). The measured results of a prototype manufactured through milling verify experimentally the numerically predicted performance.

No abstract