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Title:	Ultralow profile ceiling mount antenna for distributed antenna system application
Authors:	Ng Kok Jiunn (P83587)
Supervisor:	Mohammad Tariqul Islam, Prof. Dr.
Keywords:	Antennas (Electronics) Ceilings Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	26-Dec-2020
Description:	The Distributed Antenna System (DAS) is a promising solution to meet the needs of indoor coverage and the rising demand for capacity. In recent years, ultralow profile antennas for indoor DAS have gained increased popularity due to the high expectation of aesthetically pleasing profile when integrated into the ceiling design of the building. Besides, the spectrum has continually added into the Long-Term Evolution (LTE) and Fifth Generation frequency range as it progresses towards the next generation. Some regional authority has put the public safety DAS as an additional requirement in the indoor coverage that may include the band such as Very High Frequency (VHF), Ultra High Frequency (UHF), and 700/800 MHz. It poses a more significant challenge to cover even wider bandwidth, e.g. from 350 MHz-6000 MHz to support both cellular and public safety application with a good radiation pattern. To maximize the throughput and capacity of a modern DAS system, low Passive Intermodulation (PIM) has become a requirement too. For ultralow profile antenna, the design option limited to typical planar dipole type antenna that suffers from deep null in the azimuth plane that causes a blind spot of the coverage. The typical planar dipole antenna can be substantial in size to cover the lowest frequency of 350 MHz. In this thesis, two novel ultralow profile antenna is designed to have small size for its frequency, reduced azimuth null and low PIM to meet this niche market requirement that difficult to be achieved by conventional dipole or array antenna. Investigation of various wideband and super wideband planar dipole and monopole antenna covering the desired frequency ranges was performed to give insight to the limitation and characteristic of the antenna. Two design concepts are presented that use the asymmetrical planar dipole/monopole to achieve both wideband and azimuth null reduction radiation pattern. The first proposed antenna was designed based on asymmetrical dipole (multiple arms and gaps between the ground edge) having an inclined ground-feeding edge that covers frequency ranges of 600-4200 MHz. The second proposed antenna was developed based on shorted 2-D discone antenna with stud and fully asymmetrical structure to support down to 350 MHz range. The asymmetrical structure and the shorting lead to the miniaturization of the diameter of the antenna. This proposed antenna has superwide bandwidth with achievable band ratio of 28.57:1 covering 350-10000 MHz with reduction of the size about 62 % of the similar concept type antenna. A few variant design were investigated to arrive at the cost-effective design using hybrid material instead of the single microwave substrate material. Parametric studies using CST commercial EM simulation tool gives an insight into the performance of the antenna. Prototypes are fabricated with production quality PCB to measure achievable best PIM performance. A comparison of the radiation pattern to the convention printed dipole/monopole shows that the proposed design has reduced null at azimuth plane. The prototype measurement results conformed to simulation results. The PIM level of the antennas are measured and are below the -150 dBc meeting the industry PIM level requirement. Finally the design offers aesthetic pleasing profile option to the DAS ceiling mount antenna with least of performance impact for latest modern communication application.,Ph.D.
Pages:	181
Call Number:	TK7871.6.N465 2020 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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