Research And Design On Coplanar Waveguide Feed Ultra-Wideband Antennas With Multi-Band-Notched

Ultra wideband (UWB) wireless communication technology has attracted considerableattention in the field of short-distance wireless communication systems for next generationsdue to its high transmission speed and low bit error rate (BER), which has been extensivelyutilized and further developed in many significant domains, such as high-speedcommunication, radar tracking, distance measuring, and precision positioning and guiding.On the other hand, antenna has a decisive role in the wireless communication systems; itsproperty influences directly the performance of the whole wireless communication systems.Therefore, research on UWB antennas is definitely of great realistic significance and value ofapplication.In order to effectively mitigate the undesirable interferences generated from othernarrow-band systems within the range of the bandwidth of UWB wireless communicationsystems (like wireless local area networks (WLAN)(5.15-5.825GHz) and WorldwideInteroperability for Microwave Access (WiMAX)(3.3-3.8GHz)), UWB antennas shouldentail band-notch property. Recently, some of the most popular ways involved in band-notchgeneration include embedding slot structure, load structure, and embedding stub structure, etc.,which, however, are seriously restricted to realizing the performance within only a relativelynarrow band-range, and consequently cannot satisfy the requirement of UWB wirelesscommunication systems.In allusion to the problems mentioned above, this thesis conducts profound researchabout simple and compact small-sized UWB antenna with multiple band-notch property. Themain contributions are as follows:1. This thesis puts the highlight on the development and designing of the UWB antennasconforming to series of parameter measurements. Firstly, the structure and workingmechanism of Coplanar Waveguide fed (CPW-fed) system are systematically analyzed, andon the basis of giving the relevant formulas for designing CPW-fed structures, this thesispresents a new type of wideband CPW-fed micro-strip antenna, and verify the feasibility ofthe idea to design a wideband antenna using CPW-fed theory. Then, based on theparameter-designing index, it proposes a designing method for CPW-fed fork-shaped UWB antenna, which can provide wide relative bandwidth, robust gain and excellentomni-directional radiation property.2. In allusion to the problem of a wide coverage of interfering signal on the spectrum ofUWB signals, this thesis presents a designing method, which enables UWB antennas withsingle band-notch property to operate among the full band-range. To begin with, by the use ofmicro-strip network analysis theory, this thesis conducts deep research into three differentband-notch structures, i.e. embedding slot structure, embedding defected ground structure,and embedding stub structure. Then, it presents a novel UWB antenna based on resonanceconditions of those three structures respectively, and gives out a specific designing method onsingle band-notch microtrip UWB antennas, which can support the whole-range singleband-notch on the spectrum of UWB signals.3. This thesis explores the means of designing UWB antennas with dual band-notch andmulti band-notch properties respectively to the question of various underlying interference inUWB frequency range. Firstly, the research begins with designing of UWB antennas, which iscarried out by combing the defected ground structure and L-shaped slot structure with spreadband-notch property. Results show the combination can spread band-notch of UWB antennas.Secondly, the thesis proposes two methods to design the UWB antennas with dual band-notchand triple band-notch property respectively. One is combining the dumbbell-shaped defectedground structure and cross-shaped stub resonance structure, and the other is combing the thirdorder open circuit structure and the dumbbell-shaped defected ground structure. Theeffectiveness and feasibility of the multi band-notch generation technology also have beenverified in this paper. The results show that these antennas possess improved band-notchproperty with each notched bandwidth relatively independent and more flexible-adjusted, andadvanced capabilities of mitigating the interference from WLAN, WiMAX, RFID and C/Xwave-band systems.