Patch antenna and arrays directivity enhanced by adjacent reflective surfaces for satellite communications

Low profile planar antenna and beam steerable planar antenna have been designed to operate primarily at 30 GHz. The antenna element is microstrip patch antenna operating in the second mode, TM020. It is the first time that this mode of operation is exploited. This mode produces two symmetrical beams around the broadside, which can be combined constructively if an adjacent reflecting plane is appropriately (at 90 deg) attached to the microstrip patch substrate. The designed antenna array can be used as a gateway for LEO, MEO satellites, as a user terminal antenna, or as a 5G antenna in mobile communications. Also it is useful for Wi-Fi or IoT applications. A link budget has been calculated based on a scenario with 22 satellites and 58 satellites orbiting at 550Km above the Earth. Based on this scenario, the requirements of the antenna were generated. It resulted in a maximum required antenna beamwidth of 69.3˚ and 37˚ (depending on the number of satellites in the orbiting plane) for good adjacent satellite discrimination. This translated into an antenna gain of 8 dBi and 13.5 dBi respectively. The antenna array designed in this work exceed these specifications. The simulation results showed that by adding an adjacent reflective substrate to the microstrip patch antenna operating in the second mode, its gain can be improved by approximately 3 dB. An array of four such antennas increased the gain by approximately 6 dB. A further 2.5dB of extra gain was introduced with the addition of the reflecting patches arranged on the reflecting substrate, resulting in a gain of approximately 19 dBi and 27˚ beamwidth. By imposing 140˚ progressive phase shift at the input of each element of the array, the beam can be steered approximately 62˚ in Azimuth, for a 3 dB drop in gain.