الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
In this thesis, a novel simple compact electromagnetic band gap (EBG) configuration is proposed and analyzed using 3D finite difference time domain (FDTD) method. The proposed EBG structure consists of metallic square patches that arranged on ordered circular rings. The bandgap feature of surface wave suppression is demonstrated by calculating the transmission responses and near field distributions. from the investigated transmission curves, the surface wave bandgap is found to be 6.2 GHz and extends from 4.8 GHz to11 GHz. By inserting a 5.67 GHz patch antenna over the proposed 3-rings EBG structure, the 10 dB bandwidth has been enhanced by around 600% and the multiband ability is investigated. Further, the average value of the directivity over the wide frequency band has been improved by around 1.6 dB. On top of that, the design of 4-rings EBG structure is used to decrease the mutual coupling between two coupled rectangular patches with planar separation of quarter the wavelength by 5 dB. Much isolation between closely-packed antenna elements can be easily achieved by using more EBG circular rings. The proposed Microstrip antennas that utilize the proposed EBG structure are appropriate for WLAN applications.
In addition, reconfigurable microstrip antenna based on the proposed EBG structure has been achieved. The reconfigurability has been obtained by etching a rectangular shape slot in the patch and mounting a photoconductive switch across the rectangular shape slot. The position and the length of the switch have been optimized with the purpose of controlling the operating frequency bands of the proposed antenna. According to the incident light, the physical properties of the switch can be changed from an insulator state (OFF state) to a near-conducting state (ON state). The proposed design yields wideband that extends from 5.74 to 7.53 GHz for wireless communication applications. Further, the band of 5.3–6.9 can be eliminated from the whole frequency band.
Moreover, In this thesis, many microstrip patch antennas based on EBG structures have been simulated and the validation results show very good agreement with corresponding published results.