Development Of Wideband Circularly Polarized Antennas For Remote Sensing Microsatellite

Abstract

Chiba University is developing the GAIA-I microsatellite which makes use of the Global Navigation Satellite System (GNSS) Radio Occultation (RO) and the Electron Density - Temperature Probe (EDTP) sensors. The mission is to provide global coverage vertical resolution of pressure, temperature, refractivity, and water vapor in the atmosphere, also electron temperature and density in the ionosphere. The atmospheric parameters data will be used in numerical weather prediction (NWP) for climate modeling, while the ionospheric data will be beneficial to investigate the relationship between global land deformation and te electron density.In this research, two novel methods to generate wideband circularly polarized (CP) based on equilateral tringular ring slot (ETRS) antenna for the GNSS-RO receiver and command communication satellite of te GAIA-I are proposed. The first method is the introduction of a pair of slits to improve the CP bandwidth of equilateral tringular slot (ETS) antenna which technically is a wide slot but employs the ring slot CP excitation technique thanks to the basic shape. The small size antennas introduce chamfered corners, triangular perturbation patch and feed line with additional branches to produce wideband CP operation. A further 3-dB ARBW improvement close to its impedance bandwidth is obtained by attaching a pair of slits. It can be confirmed that the pair of slit has a significant impact to double the 3-dB ARBW and decrease te antenna size. A study on several parameters influencing the shape transformations to the impedance and axial ratio bandwidth is presented. The designed ETS antennas for both applications are fabricated to verify the simulated results. The measured antenna for communication satellite presents good agreement with the simulated one by presenting CP bandwidth of 52%. Meanwhile, the measured design for the GNSS-RO receiver performs 3-dB ARBW of 41,6%. A truncated come reflector manufactured using 3D printer offers unidirectional radiation pattern for the proposed antenna and improves te perfoemance by delivering a maximum gain of 11.9 dBic.The second method is the insertion of two diagonal line slots to improve CP bandwidth of ETS antenna. In this second antenna type, te linearly polarized (LP) ETRS is converted to circular by truncating only two slot corners and attaching grounded perturbation patch. Since tecnically become a wide slot, it is ten referred as ETS as well. However, it performs smaller 3-dB ARBW tahn its reflection coefficient bandwidth.Xii, 100 hlm. ; 28 c