Hello friends welcome to HiTech BabaJi- Simply Read & Learn. Today we will discuss about Antenna Basics & Various Types of Antennas.
ANTENNAis a device which converts electromagnetic
radiations from space into electrical currents in conductors and electrical
currents from conductors into electromagnetic radiations in space. So we can say an Antenna is a metallic structure or conductor or wire that receives or transmits radio waves.
Antenna comes in different shapes and sizes from little one to really big one. Little one which can be found on your mobile phones and really big one which receives signals from satellites, about 36000 kms away from earth surface and from deep space also.
Antennas may be divided into various categories depending upon physical structure, frequency of operation and their applications. Some of the important types of Antennas are:
1. Wire Antenna
2. Aperture Antenna
3. Reflector Antenna
4. Lens Antenna
5. Microstrip Antenna
6. Array Antenna
Wire Antenna : Wire antennas are the basic types of antennas. These are well known and widely used antennas. The following are the examples of wire antenna :
a) Dipole
b) Monopole
c) Helix
d) Loop
Applications of Wire Antenna : Personal applications like antenna at rooftop of buildings, at rooftop of automobiles, in aero planes, aircrafts and space crafts.
Aperture Antenna:
An Antenna with an aperture at the end can be termed as an Aperture antenna. Waveguide is an example of aperture antenna. The edge of a transmission line when terminated with an opening, radiates energy. This opening which is an aperture, makes it an Aperture antenna.
The main types of aperture antennas are −
Wave guide antenna
Horn antenna
Slot antenna
Aperture Antennas are used in the space communications where radiation losses are required to be very low.
Reflector Antenna: An antenna reflector is a device that reflectselectromagnetic waves. Antenna reflectors can exist as a standalone device for redirecting radio frequency (RF) energy, or can be integrated as part of an antenna assembly.
Parabolic antenna is distinguished by their shapes and size. Parabolic antenna is an antenna use a parabolic reflector. This parabolic or curved reflector surface directs the radio waves to its focal point. The most common shapes are dish antenna. The main advantage of dish antenna is its high directivity and gain.
The types of parabolic antennas are:
a) Axial or front feed or prime focus dish antenna
What is a resistor? Resistors are passive electrical components that limit electric current. Resistor is a passive electrical component. Its primary function is to limit the flow of electric current. To understand the function and working of resistors, let us consider an uniform hollow pipe with water flowing through it. If the two similar pipes are now joined with a narrow pipe relatedly having less diameter or cross-sectional area. Then the water current will be resisted by the pipe having less cross-sectional area. It means this particular section of pipe will act as a resistor for water current. Similarly, a resistor by limiting or reducing the flow of charge carrier, reduces the flow of electric current in a circuit. What is OHM’S Law? Voltage across a resistor is directly proportional to the current passing through it. V µ I or, V=R.I Where, R is a proportionality constant, it is called resistance of a resistor. It means t...
Electromagnetic or Radio Wave Propagation: The electromagnetic radiated waves Travel through different paths to reach at the receiver antenna. The path taken by the wave to travel from the transmitter and to reach at the receiver antenna is known as wave propagation. The propagation of electromagnetic waves may be divided into the following categories: 1. Ground Wave or Surface Wave Propagation 2. Sky Wave Propagation 3. Space Wave Propagation (Direct wave follow -Line of Sight propagation and indirect or reflected waves have two components: a) Reflected From Ground b) Reflected from Troposphere). Ground Wave Propagation : A ground or surface wave travels along the surface of the earth. These waves are vertically p...
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