Design And Research Of Band Notched Ultra-Wideband Antennas

The U.S. Federal Communications Commission defines the spectrum allocation of the Ultra-Wideband communications in April2002, the ultra-wideband technology of wireless communications has been greatly developed and the U WB antennas based on different structures have been proposed in recent years. With the radio frequency components highly integrated, the UWB spectrum contained a lot of wireless narrowband communication bands, so the research of ultra-wideband antenna with band-rejected characteristics has great practical value.In this thesis, the definition and the development history of ultra-wideband was introduced, The ultra-wideband antenna has been divided from the historical development and application of the direction, the ultra-wideband antenna performance parameters, indicators and other theoretical concepts are summarized, the analysis of ultra-wideband antenna approach was introduced. The two UWB planar printed antennas and six UWB antennas with band-rejected characteristics were designed under the requirements for the UWB antenna.Firstly, we designed two UWB planar printed antennas using microstrip-fed and coplanar waveguide-fed, respectively. Optimized the impedance matching of the two antennas by small-scale processing the size of the antenna by slotted on the metal ground with gradient structures and changing the floor shape, respectively.Secondly, on the basis of these two antennas, the four ultra-wideband antennas with band-rejected characteristics were designed by slotting on the radiating patch, loading minor on the radiating patch, loading resonant structure on two both sides of feed line and mushroom-shaped structure. The band-rejected characteristics were achieved by optimizing the parameters of the four structures, and the experiments would be tested accordingly.On the basis of the microstrip-fed ultra-wideband antenna, one kind of ultra-wideband antenna with dual band-rejected characteristics was designed by analyzing the stop bands performance of the different structures, the combination of load minor and the resonant structures were used and analyzed.Finally, on the basis of the coplanar waveguide-fed ultra-wideband antenna, one kind of triple band-notched characteristics ultra-wideband antennas was designed by slotting a C-shaped and U-shaped on the radiating patch and loading an SRR structure in the back of the dielectric plate. Wireless narrowband frequency bands within the UWB band, such as WiMax (3.3～3.7GHz), Wlan (5.15～5.825GHz) and ITu (8.025～8.4GHz), were rejected, the antenna tests match with the simulation results, and also has a good radiation characteristics.