| Ultra wideband(UWB) technology is widely applied for its superior performance and it is also a new short-range wireless communication technology which has received much concern at present. But, with the influence of the Federal Communications Commission(FCC) low-power specification requirement and multipath fading problem, the development of UWB technology will be restricted. Space diversity technology can obtain a larger diversity gain without sacrificing signal spectral resource and time resource, while guaranteeing the data transmission rate. The combination of UWB technology and space diversity technology can effectively overcome the shortcomings of UWB technology and make UWB to realize stable high rate transmission over a long distance. At the same time, due to the commercial UWB spectrum opened by FCC is 3.1GHz-10.6GHz, which covering many existing narrowband communication bands. In order to avoid mutual interference between the communication systems at same band, band-notched UWB diversity antenna is urgent to study.Based on the above-mentioned background, the attention of this paper is focused on the band-notched UWB diversity antenna. An band-notched UWB angle diversity antenna and three band-notched UWB polarization diversity antennas is designed by using Ansys HFSS and manufactured in the paper. The band-notched UWB angle diversity antenna achieves dual band-notched properties for the Wi MAX band and WLAN band by cutting a circular groove on the radiation patch in which a Y-shaped stub is embedded and etching a pair of hooklike slots on the ground, and obtains higher isolation between ports by embedding a pair of L-shaped stubs in the ground. Two of three band-notched UWB polarization diversity antennas consist of a circular patch monopole antenna and a U-shaped patch monopole antenna. The one antenna enables circular patch monopole antenna to get band-notched property for the Wi MAX band by adopting the same band-notched design method as the band-notched UWB angle diversity antenna used, and makes the U-shaped patch monopole antenna obtain dual band-notched properties for the C-band satellite communication band and X-band satellite communication uplink band by etching three semi-circular slots on the U-shaped radiation patch. The other antenna enables circular patch monopole antenna achieves band-notched property for Wi MAX band by etching a circular slot on the circular radiation patch, and makes the U-shaped monopole antenna obtain dual band-notched properties for the C-band satellite communication band and WLAN band by etching a pair of L-shaped slots on the U-shaped radiation patch and a U-shaped slot on the ground. Another one of three band-notched UWB polarization diversity antennas consists of two identical coplanar waveguides feeding rectangular-shaped radiating patches. The antenna achieves band-notched property for the WLAN band by etching a pair of Z-shaped slots on the ground and obtains higher isolation between ports by embedding a Y-shaped stub in the ground.The four band-notched UWB diversity antennas designed in the paper have compact size and the measured S-parameters of antennas are agree with the simulated results very well. Each of antennas has the impedance bandwidth covering almost the entire UWB bandwidth, good band-notched properties, the port isolation of better than 15 d B, moderate gain and higher radiation efficiency in operating frequency band(expect notched band). |
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