A dual-polarized planar array antenna for Ku-band satellite communications

The authors propose a low sidelobe dual-polarized planar array antenna for Ku-band satellite communications. In conventional dual-polarized planar array antennas using strip lines and microstrip patch antennas, it is difficult to obtain low sidelobe characteristics because the aperture distribution is deformed from the desired one by electrical coupling between feed lines and element antennas. In the proposed antenna, rectangular coaxial lines have been adopted as feed lines in order to reduce coupling between feed lines. We have developed a dual-polarized element antenna shielded by a cavity, in order to reduce coupling between element antennas and feed lines. Also, we have developed an element antenna arrangement forming the desired aperture distribution by adjusting the number of antenna elements in each row. These developed techniques can achieve sidelobe levels of less than -23 dB which would be lower than those of the conventional dual-polarized planar array antennas.