| With the rapid development of technology, whether military or civiliancommunications equipments are required to minimize the dimensions and increasecommunication device functions. As one of the most important parts of acommunication device, the antenna, its miniaturization and broadband antenna designhave become an important aspect of the design. However, due to the antenna electricalperformance is very dependent on the antenna structure size, the antenna size reductionwill bring the deterioration of antenna bandwidth, efficiency, directivity, quality factorand other indicators. This paper focuses on that how to realize the expendtion of thebandwidth, and does not affect the antenna directivity and other various performanceindicators, based on the miniaturization antenna design.Miniaturization of the antenna design can be achieved by many techniques, butmany of the current technology are aim to the reduction of the dimensions or resonantfrequency. So while the achievement of the miniaturization design, other characteristicsis destroyed, and this case cannot up to standard of entire demand of the moderncommunication system. To solve this problem, this paper has miniaturized the antennaby inductive load, and improved the feed of the inductively loaded antenna to expendthe bandwidth at the same time, and discussed the ultra wideband antenna with severaldifferent band-notched shaped. The works of this paper are as follows:This paper summarizes many techniques of antenna miniaturization, and mostcommon types of UWB antenna-include the characteristics of the UWB antenna,omni-directional antennas, directional antennas, multi-band antennas, impulse radiatingantennas, BAN and medical antennas.This paper found the special characteristics of antenna miniaturized by studied thedifference of the miniaturization design and the basic concept and performance of theantenna miniaturization. Next, we summarized the main methods of miniaturization ofthe antenna currently, analyzed and contrast these methods for comprehensive use.1. Study and design of various forms antenna with inductive load for reduction. Atfirst, the analysis of theoretical of reduction with inductive load is introduced, and usethe theory in one of the most common type, dipole. After the type of the inductive loadis confirmed to sleeve, the adjustable parameter is simulated and theoretical analyzed,and the dimensions of the sleeve is confirmed, and then the effects and results of thevarious sleeve is studied.35%~64%reductions is achieved by inductive load inmeasurement, with varying degrees deterioration of bandwidth. As a result, this technique is very suitable for the narrow band communication systems. Then, the typeof the inductive load is changed to suitable for the printed planar dipole.25.8%reduction is achieved without the deterioration of the bandwidth and radiation pattern.So, it can be concluded that the resonant frequency can be reduced by inductive load.2. The function and effect of the miniaturization of the antenna array by inductive loadis studied. By measurement of the LPDA with the sleeves, the total area is reduced from5.46m2to2.87m2, by47.5%without the influence of bandwidth. But the direction ischanged because the size of the element is significantly reduced. As a result, theinductively loaded technique very suitable for the miniaturization of all types antennaarray.3. A compact ultra-wideband monopole antenna with inductive load for size reducedis presented, and improves the feed line to extend the bandwidth to extremely wide band.Ring load-a different type of the inductive load is employed in the monopole, and as aresult, the smallest size of the open literatures from24×22mm2is reduced to20×16mm2, by39.3%. And the tapered shaped microstrip line is employed to feed theantenna, the bandwidth is extend from about3~12GHz to3~40GHz. This fact can provethat simple microstrip feed line could improve the matching and extend the bandwidthbeyond the bandwidth which FCC allocated. The extended bandwidth would furtherenhance the data rate of the UWB communication which has features of short range andhigh data rate.4. Based on the basic inductively loaded extremely wideband monopole antenna, adual band UWB antenna is achieved by employment of an extra structure whichresonate at2.4~2.4835GHz ISM band. The reality area of the dual band UWB antennais34.1mm×24mm, and a18.8%reduction is achieved by comparison to the similardual band antenna presented in open literatures recently. In addition, during the designprocess, the interaction of the radiation structures is weak, and this fact is important forthe follow-up design.5. A compact UWB antenna with dual band-notched for WiMAX and WLANapplications is presented. Dual band-notched is achieved by two invert-U shaped slotswhich etched on the feed line. Additional, the interaction between two slots is very weak.Therefore, in subsequent design, if necessary to suppress other interference, the slot canbe realized by only proper adjustment of the length and width.6. The Embedded Open-Circuited Stub (EOCS) and Embedded One-End-ShortedParallel Coupler (EOPC) which often be used in the band-stop filter are extend to Open-Circuited Stub Pair (OCSP). And the ultra narrow band and narrow closelyfrequency space dual band-notched is achieved by using OCSPs in proper positions.In summary, the technique which using inductive load to achieve miniaturizationdesign is throughout the paper, and then broadband antenna design is achieved byimproving the feed in the inductively loaded basic antenna. Finally, a very compact andextremely wide band monopole antenna with inductive load is presented, and a novelultra narrow band and ultra closely frequency space dual band-notched monopoleantenna with inductive load is presented. |
PDF Full Text Request