| Printed slot antennas have attracted much attention in recent years. They have the advantage offitting broadband working. It's significant to study this kind of antenna when they are used in manyfields. Based on the fact that broadband printed antenna be a highlight in antenna research, two kindof broadband printed slot antennas have been studied in this thesis. The first kind of broadband printed slot antenna is CPW-fed slot antenna. After doing somecomparison among several kinds of normal bow-tie slot antennas, a novel slot antenna namedrectangular-edged bow-tie slot antenna has been presented in this thesis, which is fed by CPW. Thecomparison results between the novel slot antenna and some other slot antennas with similarstructures show that the new structure is more fit for broadband working. The study of the novel slotantenna has two parts, which are analysis part and design part. In the analysis part, the influence ofthe coplanar waveguide feed line and antenna's parameters on the impedance bandwidth isemphasized. The relationship between antenna parameters and the method of parameter selectionare concluded. In the design part, a design method for the novel slot antenna has been proposedbase on the analysis in the analysis part, which include selecting of substrate board, antennageometry parameters and CPW feed line parameters.The second kind of broadband printed slot antennas are tapered slot antennas, including lineartapered slot antennas(LTSA), Vivaldi antennas(with exponential profile),and constant width taperedslot antennas(CWSA). They have been studied separately and their impedance and directivityperformance have been compared in this thesis. The results show that this kind of slot antennashave a relative high gain and a constant radiation patterns within the bandwidth. The impedancebandwidth of this kind of antenna is relative wide. Among the three different types of tapered slotantennas, the Vivaldi antenna's impedance performance is the best.For the slot antenna, the impedance performance can be improved by optimizing its geometryparameters. But for the gain and directivity performance, we must find another way, such as usingantenna array. So in the chapter 6 of the thesis, printed antenna array has been studied. Usingbow-tie slot antenna and tapered slot antenna as array element, the change of array gainperformance has been studied. The results show that the gain and directivity performance have bothbeen improved when using an antenna array.It is concluded from the results of this thesis that, printed slot antennas are fit for broadbandworking. For both CPW-fed slot antenna and tapered slot antenna, a broadband slot antenna can beworked out by optimizing their geometry parameters. |
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