Research Of A Typical Circular Monopole Planar UWB Antenna

In 2002, the Federal Communication Commission stipulated 3.1~10.6GHz for UWB communication frequency band. Ultra-wideband communication technology is widely used in wireless communication field because of its several advantages such as wide bandwidth, fast transfer rate, strong anti-interference and so on. It is a kind of wireless communication technology with wide bandwidth, which uses very low power spectral density signal to transmit information in short distance. In order to integrate with other systems, designing small size UWB antenna which has wide bandwidth, low cost and simple structure is necessary. Simultaneously, there are several narrowband communication systems in UWB frequency band, such as Wi MAX and WLAN band. In order to inhibit their interference to UWB communication, designing UWB antenna with band-notched function is also necessary. Based on the requirements above, this thesis mainly focuses on studying a typical circular monopole planar UWB antenna. The main works are listed as follows:(1) Two kinds of micro-strip line feed and coplanar waveguide(CPW) feed circular monopole planar UWB antenna are optimized. The antenna working frequency band is extended by changing the structure of the ground in the conditions that various performance of the antenna meet the requirements. Meanwhile, the size and structure of the antenna are optimized. In the end, the optimization model of the antenna is obtained. The simulated and measured results show that two antennas can satisfy the requirement of UWB communication.(2) On the basis of the optimized antenna, four band-notched UWB antennas are designed by adopting the method of etching slots and adding stubs, including two antennas with one stop band(cover Wi MAX band), a antenna with two stop band(cover Wi MAX and WLAN band) and a antenna with three stop band(cover Wi MAX, WLAN and Satellite communication frequency band). Two antennas with one stop band use micro-strip feed line and CPW feed respectively. The antennas with two stop band and three stop band all use micro-strip feed line. Simulated and measured results show that the four antennas can prevent the interference caused by narrow communication systems.(3) In order to verify the time-domain characteristics of the antenna, the transmission of the antennas designed in this thesis are measured, including the amplitude and phase of the transfer function and group delay. Measured results show that all antennas have good transmission characteristics and they can be used in time domain pulse signal receiving and sending systems.