Study On Novel Beam Scanning Leaky-wave Antennas

With the rapid development of the wireless communication technology, the requirements of radio signal coverage and data transmission rate for mobile terminals have became much higher, but available spectrum resources is quite limited. Beam scanning antenna can effectively increase the coverage of the radio signal and increase the efficiency of space-division multiplexing. Based on the operating principle of existing variable inclination continuous transverse stubs (VI-CTS) beam scanning antenna, the antenna structure is improved, and the radiation performance is optimized; then, two novel types of frequency scanning antennas are proposed based on the periodic slotted leaky-wave antenna and sinusoidally modulated reactance surfaces (SMRS), respectively. The main work and innovation points of this dissertation are summarized as follows:1. The operating principle of the VI-CTS antenna is studied in detail, and the methods for improving the radiation performance are proposed. By enlarging the effective radiation area of the antenna and employing the stage feeding approach, the beam width is dramatically reduced, and the beam scanning range and scanning accuracy are increased; by controlling the slot width, the radiation power distribution can be changed, and hence the low side lobe level of the VI-CTS antenna can be dramatically reduced.2. A model of equivalent magnetic-current linear-source array is proposed for predicting the radiation pattern and beam scanning performance of the VI-CTS antenna. By controlling the phase variation of each magnetic current, the actual scanning process can be simulated, and the variations of the radiation pattern and main beam scanning performance can be rapidly and efficiently calculated. In addition, the design process of the VI-CTS antenna is summarized, providing the regulation for the future study.3. Two novel types of the frequency-scanning antennas are proposed. One is based on the periodic slotted structure, composed of the series of two sections with different slot periods, which can radiate in the same direction at different frequency; another one is based on the SMRS, which can realize the frequency scanning with an angle range of50°.