Research And Design Of UWB Antenna

Ultra-wideband communications technology (UWB, Ultra-wide Band) is akind of wide bandwidth, high-speed data wireless communications technology withina short distance with very low power spectral density. U.S. Federal CommunicationsCommission (FCC) regulates that the UWB frequency range is between3.1GHz and10.6GHz, which has a total bandwidth of7.5GHz. The UWB technology has a widebandwidth, high transmission rate, immunity to interference, etc., and is widely usedin communication, radar and military fields. In order to achieve ultra-widebandantennas and other wireless transmission technology compatibility and systemintegration, we need to design a wideband, low-cost, low complexity ultra-widebandantenna miniaturization. It requires that the designed antenna has a small size, highintegration. It is a challenging task to reduce antenna size without affecting theantenna performance.According to the above requirements, in this thesis, three kinds ofultra-wideband antennas such as monopole ultra-wideband antenna, single band-stopultra-wideband antenna and dual band-stop ultra-wideband antenna have beendesigned, calculated and tested.(1) A coplanar monopole UWB antenna utilizing multi-step structure wasdesigned. The calculated results show that the antenna’s operating bandwidth is from2.32GHz to11GHz when the VSWR <2. The measured results show that theantenna’s operating bandwidth ranges from2.48GHz to11GHz when the VSWR <2.Good agreement is observed between the calculated and the measured results. Theresults show that the designed antenna has stable radiation characteristics in theoperating frequency band.(2) Both single band-stop and dual band-stop UWB antenna based on patch slotstructure was proposed.①. For the single band-stop ultra-wideband antenna, thecalculated results show that the operating frequency band is2.59GHz-4.25GHz and6.81GHz-10.91GHz when the VSWR <2. The stop-band is from4.25GHz to6.81GHz when the VSWR>2. The tested results show that the operating frequencyof the presented antenna ranges from2.54GHz to4.12GHz and6.73GHz to10.83GHz when the VSWR <2. The tested stop-band is from4.12GHz to6.73GHzwhen the VSWR>2. Both calculated and experimental results show that the designed antenna can achieve a very good interference suppression from WLAN system (5.2-5.9GHz).②. For the dual band-stop ultra-wideband antenna, when the VSWR <2,the calculated results show that the operating frequency band is of2.40-3.31GHz,3.51-5.22GHz and5.95-11GHz. The tested operating frequency band of theproposed antenna is2.36-3.32GHz,3.50-5.13GHz and6.09-11GHz. When theVSWR>2, the calculated results show that the stop-band is3.20-3.52GHz and5.14-6.01GHz. The experimental results show that the stop-band of the designedantenna is3.31-3.52GHz, and5.22-5.94GHz. The interference from the WLANsystem (5.2-5.9GHz) and WiMAX system (3.3-3.5GHz) can be well suppressed bythe designed antenna. The experimented results show that single-stopband anddual-stopband characteristics antenna can be meet the demands of the future wirelesscommunication systems.