C-band Broadband Circularly Polarized Microstrip Antenna Design

Circular polarized antenna, which has advantages in receiving arbitrary polarized electromagnetic wave, is widely used in the fields of satellite, radar, navigation, and electronic countermeasures, etc. Recently, because narrow band circularly polarized antenna is hard to meet the needs of highly developed telecommunication industry,broadband circularly polarized antenna has become a research hotspot. Currently there are some achievements on C-band (4?8GHz) broadband circularly polarized antenna at home and abroad,but most researches do not cover the entire C-band.Therefore, it has a high value in studying the C-band circularly polarized antenna.This paper aims to analyze the methods to design C-band broadband circularly polarized antenna. Through theoretical analysis method, algorithm simulation and experimental testing, this paper is figured out a designing plan of broadband circularly polarized, which has three kinds of operating band to cover the entire C-band. This paper does following tasks:First, based on the cavity model theory, the transmission properties of rectangular microstrip antenna which has truncated corner structure, are analyzed, and then equivalent circuit of microstrip antenna is gained, which turns out that truncated corner is useful to the rectangular patch circular polarization. The basic conditions to make the circularly polarized radiation design.Second, as to the typical rectangular patch antenna structure, a kind of improved rectangular patch antenna structure is designed, which applies simulation and optimization method, relied on the integration theory of resonance branch method and cutting angle method. Based on such integration theory and simulation technique as well, whether the antenna radiation properties can be the same under the same truncated corner area is proved,and a rectangular patch circularly polarized antenna improved by square truncated corners is produced. Based on the integration method of truncated corner method and slotting method, another improved rectangular patch circularly polarized antenna is designed.Thrid, those three antennas are tested by two kinds of simulation software. The results show that three antennae have achieved the expected parameter demands in 4?8GHz.Last,the designing plans of those three antennas mentioned above are available to produce corresponding physical objects and testing. Results show that the designing plan, which combines resonance branch method with truncated corner method, meets the designing requirements nicely. It can realize the polarized radiation within the range of 4?8GHz; on the other hand, due to some inaccuracy caused by manufacturing loss and testing, this result is not totally same with simulation results.Good performance frequency band breaks into two pieces: 4GHz?6GHz and 6.7?8GHz. Each relative bandwidth can get to 40% and 17.7%, and the totally available bandwidth is 3.3GHz. Because of some inaccuracy by manufacturing loss and testing,the antenna, which is designed by resonance branch method and slotting method, is different from the simulation result. Good performance frequency band breaks into two pieces: 4.6GHz?5.1GHz and 6?8GHz. Each relative bandwidth can be 10.3%and 28.9%, and the totally available bandwidth is 3.1GHz.