Research And Design Of Microstrip Quasi-Yagi Antenna

The Yagi antenna is one of the most common directional antennas with simple structure, high directivity and high gain, so it is widely used in many kinds of wireless communication system. But the Yagi antenna’s shortcomings are obvious:the antenna’s size is too big, the antenna can not be conformal with other carriers because of the metal rod-shaped structure, the antenna’s bandwidth is very narrow, all of which limit the application of the Yagi antenna in some occasions.The microstrip antennas have received much attention due to their small size, light weight and ease of combining with other devices since it was invented, the microstrip Quasi-Yagi antenna is the combination of the microstrip antenna and Yagi antenna. The microstrip Quasi-Yagi antenna possesses the characteristics of high gain and direction as the traditional Yagi antenna, meanwhile wide bandwidth, low cost and ease of fabrication are also its advantages, all of which greatly expand the applied range of the microstrip Quasi-Yagi antenna. Therefore, the research on microstrip Quasi-Yagi antennas has high practical significance. In this paper, the operating principle and implementation of the microstrip Quasi-Yagi antenna are studied, and some new microstrip Quasi-Yagi antennas and their arrays are designed.At first, the microstrip Quasi-Yagi antenna is studied in this paper including its operating principle and many implementations. A novel microstrip Quasi-Yagi antenna is designed, and this antenna’s gain and bandwidth is improved by optimizing the feed structure, attaching parasitic patch and coupled oscillator, slitting directors; In order to further improve the antenna’s gain, a 2x2 four-element array antenna is designed which is based on the novel microstrip Quasi-Yagi antenna; Secondly, a dual-polarized microstrip Quasi-Yagi antenna array is designed by adjusting the angle of array elements to achieve dual-polarization characteristics. Then, a dual-band microstrip Quasi-Yagi antenna is designed by using split ring resonator to be director to realize dual-band characteristics. Finally, a ultra-wideband microstrip Quasi-Yagi antenna is designed by using microstrip line to slot-line coupling feed and modifying the structure of the ground plane to broaden the bandwidth of the antenna effectively.In this paper, a design method is adopted which combines the theoretical analysis with optimizing by electromagnetic simulation software. According to the design results, the antennas are fabricated and measured. The final measurement results show that all the design targets of the antennas meet the design requirements.