Broadband High Efficiency Dual-Polarized Horn Antenna Array Based on Orthomode Feeding Networks for Satellite Communications

This paper proposes a wideband dual-polarized horn antenna array for Ku-band satellite communications. A modified linear spline profile horn antenna, associated with an orthomode transducer (OMT), works as a radiating element. Between the Horn and OMT, an orthogonal serrated cavity is introduced to guarantee broadband high aperture efficiency. A six-port orthomode divider (6P-OMD) is employed to provide differential feeding for both polarizations, ensuring high isolation and size. The 6P-OMD, the OMT and H T-junctions constitute an orthomode feeding network, which acquire the merits of wide bandwidth, scalability, high isolation and high cross-polarization discrimination (XPD). The feeding network, together with four horn antennas, forms a 2×2 subarray. To verify this concept, a 4×4 antenna array is designed and fabricated, and its electrical performance is measured. The array achieves a -10 dB impedance bandwidth of 38%, a peak gain of 28.2 dBi, and 80-95% measured aperture efficiency for both of the two polarizations within the frequency range of 10.5-14.5 GHz. Additionally, measurement results demonstrate that the antenna realizes over 51 dB isolation, more than 50 dB XPD and free from grating lobes.