Please use this identifier to cite or link to this item:
https://ptsldigital.ukm.my/jspui/handle/123456789/487070Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Mandeep Singh Jit Singh, Prof. Ir. Dr. | - |
| dc.contributor.author | Amer Tawfeeq Abed (P85753) | - |
| dc.date.accessioned | 2023-10-11T02:28:22Z | - |
| dc.date.available | 2023-10-11T02:28:22Z | - |
| dc.date.issued | 2018-11-28 | - |
| dc.identifier.other | ukmvital:121945 | - |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/487070 | - |
| dc.description | Given their high penetration rate, Wi-Fi and WiMAX technologies underwent significant developments in the last decade. However, serious challenges were encountered in ensuring that these technologies live up to their full potential. Since Wi-Fi and WiMAX communication devices used in urban regions, they suffer from the effect of multipath problems. Dual diversity polarisation is a method used to mitigate the effect of multiple paths. One particular challenge is designing antenna circularly polarized with wide axial ratio bandwidth in a small size and low profile. Therefore, an antenna with multi-operating bands should be designed that meets the specifications of Wi-Fi, WiMAX and ISM applications, such as high efficiency, acceptable gain, and circularly polarised radiation in a small size. This study aims to design, analyse, fabricate and validate two types of planar antenna, namely, slot and fractal geometries that can be used for Wi-Fi, WiMAX and ISM (industrial, scientific and medical) applications, which overcome the limits of the current techniques that used for circular polarisation generation. Two slot techniques, namely, ground (Q-slot) and radiator slotted (crescent slot) techniques, were used in designing novel slot antennas. The new technique was used to generate circularly polarised radiation, by cutting normal arms in the elliptical upper strip feeding line. In the second proposed slot antenna, a dual crescent shape cut into the radiator plate to provide a triple operating band that covers the frequency spectrum used for Wi-Fi, WiMAX and ISM. The first proposed fractal antenna has a new structure configured via a five-stage process. At each stage, a new modified square patch with half size of that used in the previous stage was added to shape the dual fractal-structure antenna. A formula was driven to arrange the modified patches in each iteration and improve the design of the antenna with circularly polarised radiation. The second proposed fractal antenna has a low profile, wherein the configuration of the antenna was based on three iterations. Good agreement was observed between the simulated data and the measured radiation properties of both fabricated prototypes of the fractal and slot antennas, especially at operating bands and radiation patterns. The measured results of the proposed slot and fractal antennas were validated and compared with previous related antennas reported during last 7 years based on important characteristics. The proposed antennas were considered the best because of their compact size (especially the fractal antennas), coverage of the frequency spectrum required of 2.4-2.6 GHz, 3.5-3.6 GHz and 5-6 GHz for Wi-Fi, WiMAX applications(especially the slot antennas) with wide axial ratio bandwidth which is approximately 90% of the first operating band and 45% of the third operating band for the crescent slot antenna, high efficiency (from 70% to 90%), and acceptable values of gain (2-4 dBi). The proposed fractal antennas had compact size (approximately 9% and 16% of the Q-slot and crescent slot antenna size, respectively), high efficiency (85% -90% for the meandered fractal antenna), the dual input fractal antenna displayed wide ARBW which is approximately 35% of the first operating band 2.4- 2.6 GHz and approximately30% of the second band 4.9-6.5 GHz and acceptable values of gain (2.3-2.4 dBi). All the four antennas have achieved operating band functionalities with the expected resonant mode of operation. The antennas separately offer adequate bandwidth and gain with almost stable/symmetric radiation characteristics of their corresponding band of operations that can be used for Wi-Fi, WiMAX and ISM communications.,Ph.D. | - |
| dc.language.iso | eng | - |
| dc.publisher | UKM, Bangi | - |
| dc.relation | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | - |
| dc.rights | UKM | - |
| dc.subject | Antennas (Electronics) | - |
| dc.subject | Wireless communication systems | - |
| dc.subject | Universiti Kebangsaan Malaysia -- Dissertations | - |
| dc.subject | Dissertations, Academic -- Malaysia | - |
| dc.title | Design and analysis of planar antennas circularly polarized for Wi-Fi, WiMAX and ISM communication | - |
| dc.type | Theses | - |
| dc.format.pages | 196 | - |
| dc.identifier.callno | TK7871.6.A234 2018 3 tesis | - |
| dc.identifier.barcode | 005829(2021)(PL2) | - |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_121945+SOURCE1+SOURCE1.0.PDF Restricted Access | 6.45 MB | Adobe PDF |  View/Open |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.