الفهرس 
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Abstract
Ultra-wideband (UWB) technology has recently become the primary demand for new wireless communication systems. Since then, several challenges have emerged in the design of UWB antenna systems for a variety of applications, such as high-speed wireless devices. As a result, a number of research opportunities have arisen to address the UWB antenna design challenges. Multiple-Input-Multiple-Output (MIMO) is thought to be an advantageous system for significantly increasing channel capacity without increasing either transmitted power or bandwidth. Diversity gain and array gain can be achieved by deploying two or more antennas in the transmitter and receiver. As a result, the reliability and spectral quality are enhanced. Due to the use of multiple antennas in MIMO systems, achieving high isolation of less than -15 dB between antenna elements is the primary requirement of MIMO systems. As a result, the decoupling between the antennas must be high. It must also be compatible with a wide range of integrated circuits and be small size. This thesis focuses on the design and analysis of two UWB-MIMO antenna systems with a wide impedance bandwidth (2-11 GHz) and (2-14 GHz), which achieve the desired characteristics, improve performance, and can be used in a variety of applications such as radar, Bluetooth, and wireless applications. This dissertation describes a novel proposed design for a compact wide-band monopole antenna with fourth notch band characteristics. The proposed antenna design is compact in size, the size for the first design is (40 mm × 47 mm × 1.6) mm3 and the size for the second design is (39 mm × 39 mm × 1.6) mm3, is fed by a microstrip transmission line, and it exhibits a monopolar far-field pattern in the radiating band. In order to prevent interference problems from existing nearby communication systems, some slots and slits are etched in the antenna design. The first design cancels interferences due to Bluetooth (2.2_2.8 GHz), WiMAX (3.3 –3.8 GHz), WLAN (5.1 – 5.8 GHz) and X-band (7.09-7.92GHz) frequencies and the second design cancels interferences due to WLAN (5.1 – 5.8 GHz), Lower X-band (6.9 –7.7 GHz), Upper X-band (9.3 – 9.7 GHz) and KU-band (12.2-13.1 GHz) frequencies while maintaining good gain over the UWB. At almost all frequency ranges, these findings indicate good gain flatness, good impedance matching, and omnidirectional radiation patterns. This demonstrates the effectiveness of the proposed antenna design in wide-band communication systems such as satellite communications, radar, Bluetooth, and wireless applications. Also, in this work, a new design of wide-band MIMO antenna with fourth band-notched characteristics and improved isolation is proposed. The first design of UWB-MIMO antenna consists of 4 symmetric antenna elements and is fabricated on the FR4 substrate with a dimension of )80 × 94 × 1.6(mm3. This design achieves high isolation (< -15dB) without using any decoupling elements, but it requires an orthogonal orientation of the four elements and an individual element size of )40 × 47(mm2. The second design of UWB-MIMO antenna consists of 4 symmetric antenna elements and is fabricated on the ROGER substrate with a dimension of )78 × 78 × 1.6(mm3. This design achieves high isolation (< -15dB) without using any decoupling elements, but it requires an orthogonal orientation of the four elements and an individual element size of )39 × 39(mm2. The proposed UWB-MIMO antenna’s effectiveness is demonstrated by investigating measurement and simulation results and comparing them to other existing designs. The simulated and measured results show that the two designs have a return loss less than -10dB, mutual coupling less than -15 dB, and omnidirectional radiation patterns across the operating frequency range (2 to 11 GHz) and (2-14 GHz) excluding the four rejected bands. Also, the first UWB-MIMO antenna exhibits a high diversity performance in terms of the envelope correlation coefficient (ECC < 0.06) and channel capacity loss (CCL < 0.3 bits/s/Hz). This reveals the effectiveness of the proposed UWB-MIMO antenna design in wide-band wireless applications such as satellite communications, radars systems, Bluetooth and wireless application.