Dual-Band Circularly-Polarized Microstrip Antenna for Nano Satellite

Abstract

New design of dual-band circularly-polarized microstrip antenna in L-Band and S-Band is presented and discussed in this paper. The proposed antenna is applied on nanosatellite for electron density and scintillation measurement of ionosphere. The requirements for nanosatel-lite antenna that will apply differential phase technique have specifications such as dual bands, circular polarization with axial ratio (AR) lower than 3 dB, reflection coefficient $(S_{11})$ lower than −10 dB, length and width of the antenna lower than or equal to $100 \text{mm}\times 100 \text{mm}$ . The proposed antenna is simulated based on computer simulation technology (CST) simulator with single proximity-coupled feeding, single patch, dual-band circularly-polarized microstrip antenna. The proposed antenna consists of ground and rectangular-formed radiating patch on the upper side with circularly-formed slot on the center of patch and the feeding line at bottom side. Between radiating patch, ground patch and feeding line have a substrate which have dielectric constant of 2.17, dissipation factor of 0.0005 and dielectric thickness of 1.6 mm. The investigation is performed by varying the length of feed line at bottom side and the size of parasitic rectangular patch at upper side. The length of feeding line has dominant effects to reflection coefficient of the lower band frequency and the size of parasitic small patch rectangular-formed have dominant effects to axial ratio on the higher band frequency. The characteristic of antenna parameters such as impedance bandwidth, axial ratio bandwidth (ARBW) will be presented. From simulation result, the characteristic of proposed antenna has a good agreement between simulation and antenna requirements for nanosatellite antenna to transmit the beacon signal.