Research On The Key Techniques Of Phased Array Antennas

Along with the development of society, modern satellite communications had shifted from limited stationary services to land mobile applications. The increasing demand of communicating via satellites on moving ships, boats and vehicles results in the need of high gain direction antennas which are convenient to be mounted on the carrier, and integrated of the intellectual beam forming technology, on which great efforts were put into from worldwide. Generally, phased array antennas are considered most suitable in mobile communication for its electric beam scanning ability, which is very important to maintain communication on movable objects. Thus it drives the research to investigate antenna element suitable in array constructions. Conventional techniques like parabolic antenna and reflector antenna are sensitivity to environmental influences which are undesirable as moving objects require minimum impact on aerodynamics. Planar antenna especially microstrip antenna is well suited to be used in large array antennas due to its light weight, small size, low profile and easy fabrication. During the last few years, great efforts had been put into microstrip antenna to overcome their drawbacks like narrow bandwidth and low gain, double-sided printed dipole is one of the achievements. But large array using conventional printed double-sided dipole is difficult to reach high gain. To solve this problem, this paper focuses on the design of planar array antenna for satellite reception by combining the technology of dipole antenna and microstrip antenna, and presents a series of designing principles and steps which suits the broadband and high gain antenna designs. Based on arrays combined with phased shifters, an analysis on controls of antenna beam is also made.At first, an overview of microstrip antenna is given, and the development of antennas in satellite reception is introduced. The electromagnetic simulation methods used in this study are also briefly descried.Based on the known arts, a new structure of coaxial feed double-sided printed dipole is proposed and a study of its performance by using different forms of patch as the dipole arms is carried out. We then constitute the larger antenna array through analyzing characteristics of 4 elements array and have some of them fabricated to verify our designs. A 32 elements array have reached a high gain of 22.8 dB at the center of working band while the cross polarization is below -25dB; a 64 elements array achieved a gain of 26dB; meanwhile, an analysis on how to raises the gain of a single element is made.Then, the traditional microstrip patch antenna is studied and a double patch antenna is developed. A 256 elements array is fabricated. The measured results were up to expectation.At last, an analysis is made on the electronic and mechanical tracking for the satellite signals based on the fact that the antenna units are in-phase combined, and the simulation on the control of beam under interference is carried out, which confirms that the systems can keep a firmly tracking of signal in a random noise environment.