Study Of Microstrip Circular Polarization Antennas

Due to the advantage of light weight, low profile, small volume, easy manufacture and so on,microstrip antennas have been widely used in various kinds of wireless communication technologies. But recently, because of the special requirements of the antenna applying platform, the traditional single linearly polarized antenna has been unable to meet the actual requirements, circularly polarized antenna more and more people's attention.So the study of microstrip circular polarization antennas has become an important research topic currently.The investigations of microstrip antennas are mainly about high gain circular polarization antennas, broadband circular polarization antennas and so on. Based on the research background and theories above, this paper designed several miniaturized microstrip circular polarization antennas, major works in this paper are summarized in the following aspects:1. This paper has designed a airborne low profile right circular polarization conformal antenna in UHF band which is using gradient cross cross slot to achieve the circular polarized radiation and fed by a power divider. The size of this antenna is 300mm×300mm×30mm. We use the electromagnetic simulation software Ansoft HFSS to simulate, optimize and fine tune this antenna model. The simulation result are good. the gain of this antenna is greater than-1d Bi,and axial ratio is less than 6d B in the beam coverage. Right-hand circular polarization performance is also good.2. This paper has designed a right-handed circular polarization antenna in UHF band. The size of this antenna is 324mm×324mm×324 mm. It is coupling fed by double orthogonal H slot to encourage circularly polarized waves. We use the electromagnetic simulation software Ansoft HFSS to simulate, optimize and fine tune the antenna model. The performances in simulated results are good, and the maximum gain of the antenna in working frequency points are more than 6.5d B. The voltage standing wave ratio VSWR is less than 1.5. The cross polarization performance is also good.3. This paper has designed a left-handed circular polarized antenna array in S band. Every element is rotated with 90 deg phase shift in order to achieve good cross-polarization level. We use the electromagnetic simulation software Ansoft HFSS to simulate, optimize and fine tune the antenna model. The performances in simulated results are good, and the maximum gain of the antenna in working frequency points are more than 12 d B. The axial ratio is less than 1 d B. The left-hand circular polarization performance is also good and indicators meet the design requirements.4. Combined of the two antennas in UHF band and S band which are fed by double H above together, a new antenna is constituted. We use the electromagnetic simulation software Ansoft HFSS to simulate, optimize and fine tune the antenna model, adjust the antenna model analysis, and the performances of UHF band and Sband in simulated results are good.At last, this paper summarizes the work proposed to make further research and improvement.