Study And Design On Dual-band/broadband Antennas For Ubiquitous Wireless Communication Nodes

With the rapid development of ubiquitous wireless communications, it has been universal to install antennas for transmitting or receiving indoors. In particular, with the appearance of the current technology of 5G WiFi, it is very common for indoor dual-band WiFi antenna installation, and the demand for wide band, small size, unidirectional radiation antenna is ever growing. Therefore, the development of an indoor communication antenna has important practical significance. In the thesis, novel dual-band and wideband unidirectional antennas are obtained by employing the combination of electro-magnetic dipole. The main content of this thesis can be organized as follows:1. At first, a dual-band Loop-monopole composite antenna is proposed, a conventional conical antenna is used as the initial stage of this design, the antenna is composed of two monopoles、a sectored loop and a circular ground plane. Then the antenna is simulated by Ansoft HFSS simulator for its reflection coefficient、current distribution and radiation pattern, it is demonstrated that unidirectional antenna with multi-mode characteristic can be obtained due to the combination of loop-monopole.2. On the basis of the former loop-monopole composite antenna, by introducing vertical reflector、changing the structure of the ground plane and the radiator, then use the Ansoft HFSS to optimize the performance, according to the simulation results, the antenna prototype is fabricated. By comparison of the measured results and the simulated one, it is founded that both agrees quite well.3. By modifying the structure of the vertical reflector and the ground plane under the condition of keeping the radiator unchanged, single-band wideband antenna is achieved. Compared to the previous design, wider operation band and better directional radiation characteristics can be achieved.