Basic Types of AntennasДЄntennas may be divided into various types depending upon в€’ДЇollowing are the types of antennas according to the physical structure. The power from the transmission line travels through the waveguide which has an aperture, to radiate the energy. The above diagram represents a waveguide, which acts as an antenna. This can be well understood by observing the following diagram в€’ These are especially used for the microwave transmission or reception. The device or tube, if bent or terminated to radiate energy, then it is called as waveguide. If this transmission line has current, which accelerates or decelerates with a timevarying constant, then it radiates the power even though the wire is straight. If the power has to be radiated, though the current conduction is with uniform velocity, the wire or transmission line should be bent, truncated or terminated. A transmission line conducting current with uniform velocity, and the line being a straight one with infinite extent, radiates no power.ДЇor a transmission line, to become a waveguide or to radiate power, has to be processed as such. For example, a wire, which is connected to an antenna. The functioning of an antenna depends upon the radiation mechanism of a transmission line.ДЄ conductor, which is designed to carry current over large distances with minimum losses, is termed as a transmission line. Antenna (whether it transmits or receives or does both) can be connected to the circuitry at the station through a transmission line.

The sole functionality of an antenna is power radiation or reception. This process would obviously be easier than laying a wiring system throughout the area. In the above image, the antennas help the communication to be established in the whole area, including the valleys and mountains. Antenna is the key element of this wireless technology. The evolution of wireless technology has made this whole process very simple. In order to contact a remote area, the wiring has to be laid down throughout the whole route along the valleys, the mountains, the tedious paths, the tunnels etc., to reach the remote location. Antenna has the capability of sending or receiving the electromagnetic waves for the sake of communication, where you cannot expect to lay down a wiring system. In the field of communication systems, whenever the need for wireless communication arises, there occurs the necessity of an antenna.

In this chapter, you are going to learn the basic concepts of antenna, specifications and different types of antennas. There are many types of antennas depending upon their wide variety of applications.ДЇollowing pictures are examples of different types of Antennas. Now-adays, antennas have undergone many changes, in accordance with their size and shape. In two-way communication, the same antenna can be used for both transmission and reception.ДЄntenna can also be termed as an Aerial. What is an Antenna ?ДЄn Antenna is a transducer, which converts electrical power into electromagnetic waves and vice versa.ДЄn Antenna can be used either as a transmitting antenna or a receiving antenna.ДЄ transmitting antenna is one, which converts electrical signals into electromagnetic waves and radiates them.ДЄ receiving antenna is one, which converts electromagnetic waves from the received beam into electrical signals. The device, which converts the required information signal into electromagnetic waves, is known as an Antenna. However, if two people want to communicate who are at longer distances, then we have to convert these sound waves into electromagnetic waves. Here, communication takes place through sound waves. The following illustration shows two individuals communicating with each other. A person, who needs to convey a thought, an idea or a doubt, can do so by voice communication.

Model noise with directivity in cadnaa