Introduction Of The Antenna Systems

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INTRODUCTION 1.1 Antenna Systems: Depending on the number of antennas used in the transmitting and receiving sections, the systems are divided into 4 types. 1.1.1 SINGLE INPUT SINGLE OUTPUT (SISO): Fig 1.1.1: SISO In SISO, there will be only single transmitter and a single receiver. This is the general system which we use. The simplest antenna technology is SISO. In some environments, this system is vulnerable to problems caused by multipath effects. When an electromagnetic field (EM field) is met with obstructions such as hills, buildings, utility wires, and canyons the wavefronts are scattered, and thus it take multi paths to reach the destination. Fading, cut-out (cliff effect), and intermittent reception (picket fencing) are the problems caused by late arrival of scattered portion of signals. In a digital communications system, it cause a reduction of data speed and number of errors is increased. In order to eliminate or minimize problems caused by multipath wave propagation, a new technology has been introduced and it is Smart Antenna Technology. There are three forms of smart antenna, known as SIMO (single input, multiple output), MISO (multiple input, single output), and MIMO (multiple input, multiple output). 1.1.2 SINGLE INPUT MULTIPLE OUTPUT (SIMO) : Fig 1.1.2 : SIMO In SIMO, there will be only single transmitter and many receivers. 1.1.3. MULTIPLE INPUT MULTIPLE OUTPUT ( MISO): Fig. 1.1.3 : MISO In MISO there will be multiple transmitters and a
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