Research On Dual-band Circularly Polarized Stacked Microstrip Antennas

With the development of modern communication technology, the antenna plays an important role as a key component of wireless communication system. The simple line polarization has been unable to meet the demand of modern communication systems, so the circular polarization antenna has been widespread concerned.Circularly polarized antenna can receive any line polarization wave, the use of circular polarization wave can reduce the impact of the reflected signal, and it can suppress the interference and multi-path reflection when used in mobile communication. Because of these characteristics of the circular polarization antenna, it can be widely used in communication, radar, electronic warfare, electronic reconnaissance, radio and television.This paper mainly works about the following three parts:The first chapter and the second constitute the first part, which mainly introduces the research status of circular polarization antenna, then we do some research about the theory of microstrip antenna, circularly polarized antenna, such as the working principle and the analysis method of microstrip antenna, the realization method and the analysis method of dual-band microstrip antenna. At last we introduces some characteristic parameters of circular polarization antenna, and the common methods to achieve circular polarization as the theoretical foundation for the design and simulation of the research.The second part is the third chapter, we introduce three kinds of simple single feed circularly polarized microstrip antenna, and the design steps of these three kinds of antennas are given. The form of the rectangular cut microstrip antenna has the best circular polarization performance, the relative bandwidths of 10-dB return loss and 3-dB axial ratio for the antenna prototype are about 4.3% and 1.6%, the gain of this kind of antenna is about 6.75dB. Compared with other forms of the single feed circularly polarized antenna, corner cut rectangular circular polarization antenna has the better impedance bandwidth and gain. Then we choose this kind of CP micristrip antenna to do the simulation design of the third part.The third part is the design of dual-band circularly polarized microstrip antenna with layered structure, which has the same feeding mode by feed the up patch and the down patch can also obtain a good match with the coupled field between the two patch. The two antennas have different structure. The first structure of the antenna is the circular patch on the top and the lower is the rectangular patch, and the antenna is slotted to achieve miniaturization. The bandwidths of 10-dB return loss of the low frequency is 2.4% and the 3-dB axial ratio for the antenna prototype are about 0.7%, while the high frequency is 3.6% and 0.8%. The gain of the low frequency is 1.76dB and the high frequency is 3.8dB. The second structure of the CP microstrip antenna is the two layers with rectangular patch, which the low frequency relative bandwidths of 10-dB return loss is 2.42% and 3-dB axial ratio for the antenna prototype are about 0.6%, while the high frequency is 2.24% and 0.6%. The gain of the low frequency is 5.6dB and the high frequency is 6.5dB. At last we test the antenna, the measured results of the impedance characteristic, the antenna radiation characteristics, and so on shows that the performance parameters and the design results are basically the same.