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Title:	Design and fabrication of 3D undirectional antenna for microwave imaging applications
Authors:	Md. Amanath Ullah (P86160)
Supervisor:	Mohammad Tariqul Islam, Prof. Dr.
Keywords:	Antennas (Electronics) Microwave imaging Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	28-Feb-2019
Description:	Microwave imaging is a technique to identify hidden objects from structures using electromagnetic waves. Advantageous features such as non-invasive and nonionizing make microwave systems attractive to scientists. Antenna is one of the most important apparatus of a microwave imaging system. Researchers specified some antenna properties as requirements for microwave imaging like unidirectional radiation pattern, frequency range within 1–4 GHz, and small dimension. Existing microwave imaging systems widely use microstrip patch antenna that inherently lack in terms of gain, bandwidth and radiation pattern in lower microwave frequency. It is difficult to achieve unidirectional radiation pattern in patch antenna and their prototype development is very expensive. Though substrate based 3D antenna can address some problems of patch antenna, the development cost increases due to utilization of multiple substrate and fabrication method becomes sophisticated. This research is aimed to design and development of 3D antenna in context of microwave imaging which can be affordable for primary health observation. Three unidirectional 3D antennas have been presented for the application of microwave imaging. Basic design methodology evolved from folding technique. Two of the designs used stacked type radiating element. The reflector walls help to achieve higher gain and directive radiation. The other one uses folded radiating element and a reflector wall behind the radiating structure. A reflector wall perpendicular to the ground plane has been introduced to achieve higher gain and directive radiation pattern. Folding technique is utilized to reduce the overall antenna size and to get resonance at a lower frequency. The first prototype operates at 1.67-1.74 GHz with a peak realized gain of 5.2 dB and front-to-back ratio of 20 dB. The second prototype operates at 1.55-1.68 GHz with peak realized gain of 4.5 dB and front-toback ratio of 15 dB. The third prototype achieved enhanced bandwidth operating at 2.37-3.70 GHz with a front-to-back ratio of 18 dB and 4.52 dB peak realized gain. Two prototypes of the antennas are used to perform an experiment to detect presence of a malignant tumor in human tissue phantom through the application of feasible signal processing technique. Based on the results, it can be concluded that high gain in lower microwave frequency, good radiation characteristics with unidirectional radiation pattern and high radiation efficiency make the proposed antennas tremendously eligible to be applied in microwave imaging.,Master of Science
Pages:	91
Call Number:	TK7871.6.U445 2019 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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