PhD Theses

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Browsing PhD Theses by Subject "Antennas"

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    Dual-Band and triple-Band printed monopole antennas for multiple input multiple output application
    (University of Dar es Salaam, 2014) Iddi, Hashimu Uledi
    The use of Multiple-input Multiple-Output (MMO) system in wireless communication is becoming increasingly popular nowadays in current research trends due to increase in traffic capacity without the corresponding increment in bandwidth and power transmission. Deploying MIMO can enhance performances of traditional wireless communication as it takes the advantage of rich multipath environment to increase the system capacity. However, the needs of multi-frequency bands for MIMO application can present a difficult task in antenna design. The limiting factors for MIMO application can present a difficult task in antenna design. The limiting factors for MIMO system implementation in wireless communications are correlation and mutual coupling between the antenna elements and the direct line-of- sight (LOS). These parameters and antenna design have significant effects on the MIMO system performance. In this research work, design and performance analysis of the printed monopole antenna for MIMO application is conducted. Two antennas have been designed for MIMO application. Initially, the dual-band B-shaped monopole antenna operating at dual-band frequencies (2.45 and 5.8 GHz) has been designed and fabricated. The impedance bandwidths achieved are 29% and 33.8% for 2.45 GHz and 5.8 GHz bands respectively. The mutual coupling and correlation coefficient have also been investigated in which the antenna provides – 22 dB of mutual coupling and 0.02 of correlation coefficients at a separation distance of A/12 between antenna elements. Subsequently, a triple band CPW-fed planar monopole antenna has been designed which operates at 2.4 GHz, 3.5 GHz and 5.8 GHz. The antenna provides measured – 10 dB bandwidths of 200 MHz for the 2.4 GHz, 620 MHz for the 3.5 GHz; and 1.38 GHz for 5.8 GHz. moreover, the antenna provides measured gain of 3.88, 4.64 and 4.57 dBi for 2.4, 3.5 and 5.8 GHz, respectively. Finally, performance analysis of these antenna arrays has been done using channel measurement. The channel capacity of these antenna arrays has been done using channel measurement. The channel capacity of 9.72 and 4.92 bps/Hz using B-shaped antenna array at 2.4 and 5.8 GHz respectively, for non-line-of-slight (NLOS) was achieved. For the LOS conditions, the channel capacity of 9.54 and 4.61bps/Hz was obtained at 2.4 and 5.8 GHz frequency band respectively. Moreover, the capacities of 8.35 and 8.00 bps/Hz were obtained for the NLOS conditions using CPW-fed monopole antenna at 2.4 GHz and 5.8 GHz respectively. For the LOS conditions, the channel capacity of 6.94 bps/Hz and 5.9 bps/Hz was obtained at 2.4 and 5.8 GHz frequency band respectively. The research contribution here is the realization of the dual-band B-shaped antenna and a triple band CPW-Fed planar monopole antenna to cover the IEEE 802.11a/b, WLAN 2.4 GHz, 5.8 GHz and WiMAX 3.5 GHz for MIMO application that can increase the channel capacity.