| In recent decades, with the rapid development of mobile communication technology and microwave and millimeter wave technology, As the key part of communication system, antenna is facing more and more technical difficulties. In order to facilitate the integration with communication systems and prevent interference between antennas which operate in the same frequency band, the technologies for antenna’s miniaturization and multi-frequency become more and more important.Microstrip antenna, with the advantages of small size, light weight and low profile can meet the requirements of miniature, multi-band and broadband.This thesis discussed the basic theories of microstrip antenna, and summarized the the developing situation of microstrip antenna, then summarized the main techniques for antenna’s miniaturization, broadband and multi-frequency. According to these theories, three miniature broadband multi-band antennas are proposed. The first antenna consists of a ring, an L-shaped branch and three branches which are loaded on the ring. It can work at GSM900/GSM1800/WLAN/WIMAX. The second antenna consists of a T-type structure and a bend branch on the top of the T-type structure. This antenna can work at GSM/UMTS/WLAN/WIMAX. The last antenna consists of a short microstrip feedline, a trapezoidal radiation patch, and an U-shaped branch. The broadband and multiband operations are achieved by the U-shaped branch and the slots which are loaded on the trapezoidal radiation patch; the proposed antenna can work at GSM/DCS/PCS/UMTS/LTE/WLAN/WIMAX.In this paper, Ansoft’s electromagnetic simulation software—HFSS is used. some parameters which can influence the performance of the antennas are analyzed. Good impedance matching is obtained after HFSS’s optimization simulation. At last, the three antennas are fabricated and tested. The simulation results agree well with the measured results, which demonstrates the designed antennas can meet the requirements of miniaturization, multi-band and broadband. |
PDF Full Text Request