Study Of The Miniaturization Technology Of Circularly-polarized Microstrip Antenna

Antenna is a significant element in wireless communication systems, which decideswhether the wireless signal can be received by the systems or not. As the fast developmentof the large scale integrated circuits and micro-electronic technology, and for someapplications, such as the demands for invisibility in cars and low-air-resistance in aircrafts,it’s a urgent technical requirement for the miniaturization of antennas. As for therequirements for the miniaturization of circularly-polarized microstrip antennas, this thesisgives some efficient ways as follows:1. A new kind of antenna for Compass and GPS system is proposed. The antenna hasminiaturized structure, includes shorting walls and double-layer with u-slots. In the B1&B3band in Compass and L1band in GPS, the antenna shows a good impedance matching,wide beamwidth and good axial ratio in main radiation hemisphere, and stable gain. Thesize of the antenna is just0.210×0.210×0.060, the impedance bandwidth are2.1%and1.5%in lower and upper bands, respectively. And the3dB AR band can cover theimpedance band in lower and upper bands, too. The new antenna is a compact structurewhich can be applied for mobile handsets.2.Two kinds of antennas applied for the satellite communication are proposed: one is aminiaturized U-slot wideband LHCP microstrip antenna. The size is just0.280×0.280×0.050. the impedance bandwidth is7.37%, AR band also covers the impedance band;the other one is a dual-band dual circularly polarized double-layer microstrip antenna fortimesharing working. The center frequency in lower band is1.995GHz and the impedancebandwidth is1.5%,which has a RHCP; while the enter frequency in lower band is1.995GHz and the impedance bandwidth is1.5%,which has a LHCP. The3dB ARbandwidth can cover the impedance band in lower and upper bands, respectively.