Study Of Dual Circularly Polarized Microstrip Antenna

Microstrip antennas are widely used in wireless communication systems for itscompact size, low profile, low weight, ease to fabricate and to be integrated with othermicrowave circuits. Specially, circularly polarized microstrip antenna is more attractivebecause of the rapid development of satellite positioning system and its wide application.Two kinds of circularly polarized microstrip antennas are studied in this paper forBeidou satellite navigation system.The first antenna we designed is consisted of two units, which are for transmittingand receiving respectively. The band for transmitting is L band (1616±5MHz) with lefthand circular polarization(LHCP), and the band of receiving is S band (2492±5MHz)with right hand circular polarization(RHCP). The two units are all designed with highdielectric constant PCB, and they are integrated to reduce the size. To improve the lowelevation radiation, two parasitic metal strips are used on the antenna radome. Goodisolation is obtained by filling the PTFE material between the transmission andreceiving unit. The measured data achieves technical requirements.The other is dual circular polarization stacked microstrip patch antenna withdual-band. The operation frequencies are at B1(1561±4MHz) and B3(1268±4MHz)bands. The upper patch is fed with a probe and the lower patch is the parasiticcomponent without feeding. Four folded cross slots are embedded in both patches totuning the resonant frequency. The simulation results are shown in the paper and theparameters of them can satisfy the design requirement.