Planar Ultra Wideband Antenna Design Using Narrow Slot Structure

Antenna is located at the front of the wireless communication systems, it is a converter between electromagnetic waves in free space and in guided-wave system, also a bridge for connecting the free space and the local circuit via electromagnetic waves. The importance of antenna is rising day by day with the rapid development of wireless communications technology today, so the performance of antennas is crucial to the whole communication system. Slot antenna occupies a important role in the whole family for its useful characteristics such as small size, wide bandwidth and low cost. In this thesis, we have designed three novel ultra wideband narrow slot antennas, completed the antenna miniaturization and the tuning technique of antennas’ input impedance.The main work of this thesis includes three parts: First, based on the former research and conclusion on the equivalent circuit model of slot antenna, we use the multi-resonance mode of antenna’s structure in its slot and coupling feed to achieve the goal of super-wideband. With using the above properties, we design and implement a super-wideband narrow slot antenna, the experimental results show that the operating bandwidth of the antenna is 3.8-20 GHz, the fractional bandwidth of the antenna is about 140%; secondly, with the study of input impedance in antenna’s coupling feed, using the Smith Chart tool, we design and implement a narrow slot ultrawideband antenna which input impedance is 50 ohms, the antenna without the need for the extra impedance matching network and the structure is more concise,the results of simulating show that the fractional bandwidth of the antenna is about 96.2%; at last, with the input impedance variation from antenna coupling feed, we design and implement a ultra-wideband planar antenna with smaller narrow slot, the gap width of the antenna based on the original shrink by about a third,while the bandwidth of antenna is nearly unchanged.