chapter  4
22 Pages

Developments in Ultra Wideband Antenna Theory

Antenna Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.6 Theory of Planar Monopole Antenna from a Microstrip

Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.6.1 Microstrip antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.6.2 Planar monopole antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

4.7 Planar Monopole Antenna from a Cylindrical Monopole Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.7.1 Resonance frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.7.2 Lower cut-off frequency for different planar antenna

shapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 4.7.2.1 Example 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 4.7.2.2 Example 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 4.7.2.3 Example 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 4.7.2.4 Example 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

4.8 Some Factors That Influence UWB Antenna Performance . . . . . . 76 4.8.1 Influence of the radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4.8.2 Ground plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

As has been shown in previous chapters, there are different approaches to designing UWB antennas. Particular types have been proposed for different applications, from wireless mobile communications and body area networks,

Methodologies,

to spectrum monitoring applications. Of all these UWB antennas, some have become more popular due to their performance and compact structure.