Miniaturized Antenna for Satellite Broadband Application

Abstract

User antenna is a crucial component of a high-speed satellite internet system. High directivity, broadband characteristics, and circularly polarized radiations are essential for a user antenna to maintain a reliable connection with the overhead LEO satellite constellation. For commercialization and portability, the antenna is preferred to be planar, lightweight, and low-cost. This thesis expands on a type of complementary antenna, designed for 26-30 GHz, which is chosen for the application after an extensive survey of wideband, circularly polarized antenna elements. The magneto-electric dipole antenna or MEDA is a broadband antenna and can be made linearly or circularly polarized depending on the application. Although MEDA also offers a stable gain of 8.5 dBi over the desired range of frequencies, yet it is not high enough for the satellite internet application. Cavity antennas with different types of superstrates are explored here to increase the directivity of the MEDA element. An optimized cavity antenna is presented, with MEDA as a primary radiator, and 5.5 dBi of gain enhancement is reported. Electrical steerability is essential for a user antenna to connect to the LEO satellite constellation, requiring an array of antennas. An array is also needed to increase the total gain of the antenna. However, due to the large size of MEDA, the antenna element cannot be arranged in a planar lattice without generating grating lobes. A novel dielectric material with relative permittivity of 5.7 is coated on the MEDA to significantly reduce the size of the antenna without disrupting its broadband characteristics, to make the MEDA compatible with planar array configuration. The miniaturized antenna element is fabricated in an external facility, whereas the dielectric material is developed in-house. Simulations were conducted with ANSYS EDT (HFSS), which agree with the measured results.