On The Frequency Band-Notched Ultra-Wideband Antenna And Miniaturized Multi-Band Antenna

The design of the frequency band-notched ultra-wideband antenna and theminiaturized triple band antenna are presented in this thesis. Two types of ultrawidebandantennas with frequency band-notched characteristics are discussed and acompact triple band antenna is analyzed on the basis of an ultra-wideband antenna. Thebrief content of the thesis is as follows:Firstly, the requirements of the frequency band-notched ultra-wideband antennasare described. In order to satisfy the requirements, a novel wide-slotted antenna and amicrostrip fed monopole antenna are employed along with half wavelength and (or)quarter wavelength resonators. The commercial software Ansoft HFSS^TM facilitates theprocess of modeling, simulation, and obtaining the optimal dimensions. Prototypes ofthe antennas are fabricated and measured. The results through out 3.1-10.6 GHz(withoutthe frequency notched bands) can be summarized as follows: (a) VSWR≤2; (b) the Hplaneradiation patterns are nearly omni-directional; (c) both the peak gain and thetransfer function maitain relatively steady; and (d) the group delay keeps in 1nanosecond; VSWR, peak gain, transfer function and group delay decrease sharply inthe vicinity of the frequency notched bands, which indicate that the presented antennashave gained good performance for band-notched ultra-wideband applications.Secondly, a compact groove-loaded triple band antenna is designed based on theultra-wideband antenna. HFSS is also utilized to analyze and optimize the dimensions ofthe antenna. A prototype of the antenna is manufactured and tested. The simulated andmeasured results reveal that the presented antenna with a miniature size of30×20×1.6mm³ achieves three pass bands for S₁₁≤-10 dB, namely 2.39-2.69 GHz, 3.21-3.70 GHz and 4.75-6.0 GHz. During the three pass bands, the normalized crosspolarizationlevel is less than -15 dB, the H-plane radiation patterns are almost omnidirectional,and the average gains are 1.3 dB, 1.46 dB, and 1.51 dB, respectively. Thedata above demonstrate that the compact triple band antenna is a good alternative forWLAN and WiMAX applications.