| With the fast development of modern electric technology, antenna, as a signal radiation device draws more and more attention for both military and civil use and develops too much. Nowadays, the commercial use of antenna, like car warning radar, wireless communication and RF identification system raises to a higher level, especially to the controllable flexibility of antenna direction chart. Phased array antenna adapts to the requirements with its flexiblly wave velocity control and rapid scanning frequency. However, much of these phased array antennas are complicated and expensive with many basic units. This paper was developed from some key elements of digital phase shifters to antenna design based on such discussion.Phase shifter is the key device of phased array antennas. A digital phase shifter is necessary to change the phase difference between elements of antenna to obtain the desired radiation pattern, moreover, phase shifter plays a great important role to scanning speed and precision of phased array antennas. To the digital phase shifter, more bits of phase shifter will control the scanning beam much more easily. However, it is more difficulty to design a digital phase shifter with more bites at a higher operation frequency. Also this will increase the cost of digital phase shifter. Thus, a good digital phase shifter with high performance and low cost is very useful.This article will focus on the five digits of Ku-band phase shifter.This paper first analyzes the various major phase shifter circuits, including loading linear phase shifter, switch linear phase shifter and reflective phase shifter, analysis and comparison of various circuit, select each phase shifting of the unit circuit design. At the same time, this phase shifter switching circuit choose PIN tube, so the analysis introduces the working principle and the equivalent circuit of the PIN. Through various phase shifter structure analysis and experiment, and ultimately chose a selection of11.25°,22.5°and45°phase shift circuit to load the linear structure, while the90°reflection type circuit,180°linear structure using switch, which can effectively improve the accuracy and phase shift in wave ratio, and helps to phase shifter miniaturized and low cost. Through the efforts of this article, the final design of five digits phase shifter, cascade after its maximum phase shift error of3.8°, insertion loss is less than3dB.For phased array antenna, this paper designs a new type of small size circular polarization microstrip antenna. Its working band for S band, center frequency selected for2.45GHz, bandwidth for50M. The frequency of phased array antenna or the adaptive array antenna has a large market demand, such as RFID in microwave frequency band work center frequency is2.45GHz+40M, but the design and the research cannot meet the needs of the market. So the work of this paper has important practical value.This article will use the circular microstrip antenna design a small patch of the size of the antenna, then the battle group, in order to make its can be used for phased array antenna. This paper realized the main principle is round polarization through a single point feeder, opening the patch of antenna aperture to stimulate the rectangular equal amplitude, phase differ90°of Jane and mode, so as to realize the circular polarization. And then based on the meandering technology, the patch slot and change shape structure patch edge, thus introducing perturbation causes a current to flow twists and turns, increase the effective length patch, reduce the size of the antenna. Finally after simulation analysis, the actual production of the antenna size and similar material produced the antenna was reduced by15%, and completed the miniaturization of antenna design... |
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