Research On The UWB Antenna With Dual Band Rejections Based On The SRR/CSRR Structures

Since the Federal Communications Commission (FCC) authorized the unlicenseduse of ultra-wideband (UWB, range of3.1~10.6GHz) for commercial purposes, UWBtechnology has developed rapidly. However, the frequency range for UWB systems willcause interference to the existing communication systems such as the worldwideinteroperability for microwave access (WiMAX3.5GHz) and the wireless local areanetwork (WLAN5.2/5.8GHz) bands. Therefore, the requirement for UWB antenna withband-notch characteristic is increasing.In this thesis, UWB antenna with rejected function is studied. Based on Babinetprinciple, the resonance characteristics of SRR (Split Ring Resonator) and itscomplementary structure (CSRR) is analyzed, and then two types of UWB antenna withband rejection are designed with the help of the commercial electromagnetic simulationsoftware Ansoft HFSS. Both the antennas have simple structures and are easyfabricated.First of all, a novel UWB planar monopole antenna with dual band rejectedcharacteristic is proposed. The two stopbands are generated by etching two squareCSRRs in the radiation patch. The proposed antenna achieves dual band rejection forWiMAX (3.4~3.6GHz) and WLAN (5.1~5.9GHz), which can eliminate the interferenceamong UWB systems and WiMAX/WLAN systerms. It also has good radiationperformance and time-domain characteristic during the working bands.In addition, a microstrip slot antenna with SRR structure is proposed. The antennacovers the entire UWB frequency band and realizes dual band band-notched functionfor WiMAX(3.4~3.6GHz) and WLAN(5.2~5.85GHz). It shows good omnidirectionalradiation patterns in the H-plane and has good time-domain characteristic as well.The antennas are fabricated and tested by vector network analyzer, and themeasured and simulated resultes show good agreement.