There must be many of us who must have heard about the antenna, many must have seen it because a few years ago almost all of us had a TV antenna installed on the roof for the TV, and sometimes if due to the wind. Don’t ask if that antenna spins, it was very annoying, where one man used to watch TV downstairs while the other used to go up and straighten it. What were those days really?
There has been a lot of difference between that time and now. The present antennas work on satellite TV, whose data reception is directly from the satellite itself. The antenna is mainly designed to receive signals. When a broadcasting station broadcasts a message, then only with the help of an antenna those signals can be received and seen on Television.
To understand the complete technology and to know about what is Antenna and its type, you have to read this article completely. Often students do not get the right sources to understand the basics of antenna, so today I thought why not explain to you guys what is an antenna is and how it works in Hindi so that it will be easy for you to understand the rest of the technology. Be. Without delay let’s start.
What is Antenna?
An antenna is a type of device that is used to transmit and receive electromagnetic waves. Electromagnetic waves are often known as radio waves.
Most antennas are resonant devices, which operate efficiently in a very narrow frequency band. For an antenna to operate properly, it has to be tuned (matched) with the frequency band of the same radion system to which it is connected, failing which both reception and transmission will be interrupted.
The antenna is used to efficiently radiate electromagnetic energy and that too only in desired directions. Antennas behave in a way like matching systems between souces of electromagnetic energy and space. The main purpose of these antennas is how to always optimize this matching.
Let us know briefly about some basic properties of antenna:
1- Field intensity is for all directions (according to the pattern of the antenna).
2- The total power that is radiated when the antenna is excited by some current or voltage is called intensity.
3- How much power was radiated and the ratio of total power is called Radiation Efficiency.
4- Antenna’s input impedance is always for maximum power transfer (matching).
5- The bandwidth or range of frequencies of the Antenna on which all these properties depend is almost constant.
All antennas are used to receive or radiate energy.
history of antenna
By the way, the history of Antenna is very old. Let us know something in this regard. The first experiment was done by Faraday in the year 1830 in which he did the coupling of electricity and magnetism and in which he showed that there is a definitive relationship between them. For this, he slid a magnet around the coil of wire, which was attached with the Galvanometer.
When he moved the magnet, he found that a time-varying magnetic field is produced and also it was found from the Maxwell equations that a time-varying electric field is also generated. In this the coil acted as a loop antenna and received that electromagnetic radiation, which was detected by the galvanometer – this is completely the work of an antenna.
The interesting thing in this is that till that time no one knew about electromagnetic waves.
Heinrich Hertz developed a wireless communication system in which he forced an electrical spark to occur between the gap of the dipole antenna. He used a loop antenna as a receiver and similarly observed disturbance.
This thing happened exactly in 1886. Whereas in 1901, Marconi sent information across the Atlantic. He attached many vertical wires to the ground at the end of a transmitting antenna.
In 1906, Columbia University built one such Experimental Wireless Station where they used a transmitting aerial cage. This cage was also made of wires and was suspended in the air.
After that many similar experiments were done and according to the dates I have written below:-
- 1 . Yagi – Uda Antenna, 1920
- 2 . Horn Antenna, 1939
- 3 . Antenna Arrays, 1940
- 4 . Parabolic Reflectors, the late 1940s में
- 5 . Patch Antennas, 1970
- 6 . PIFA, 1980
After that this process continued and many such changes took place in antennas and the antenna we are using now, we came to know only after learning from all these antennas.
type of antenna
Although there are many types of antennas, they are mainly divided into three broad categories: omnidirectional, directional, and semi-directional.
1. Where Omni-directional antennas propagate in all directions.
2. The other is semi-directional antennas that propagate in a constricted fashion, and are defined at a specific angle.
3. The third is Directional antennas which have a narrow “beam” that allows highly directional propagation; The familiar types are parabolic and Yagi. All of them have unique characteristics and applications.
Dipole Antennas या Rubber Ducky Antenna
These Dipole antennas are a very common type of antenna and they are also omni-directional, they propagate radio frequency (RF) energy 360 degrees in the horizontal plane. These devices have been made in some way so that they are resonant at the frequency of half or quarter wavelength which is applied to it. This antenna is very simple in which two pieces of wire cut are of proper length and encapsulated.
This configuration is commonly referred to as “rubber ducky” antenna. This dipole is used in many enterprise and small office, home office (SOHO) Wi-Fi deployments.
Directional and semi-directional antennas focus primarily on narrow beams to radiate power, adding a significant amount of gain to the process. Antenna’s properties are also reciprocal.
The characteristics of a transmitting antenna, such as impedance and gain, are applicable over a receiving antenna. That is why the same antenna is used for both sending and receiving.
The advantage of this highly directional parabolic antenna is to amplify weak signals; This is the reason why this type of antenna is often used for long distance links.
Patch Antenna या Microstrip Antenna
A patch antenna is a type of semi-directional radiator in which a flat metal strip is mounted above the ground plane. The radiation that emanates from the back of the antenna is effectively cut off with the help of the ground plane, so that its forward directionality can be enhanced. This type of antenna is also called microstrip antenna.
It is typically rectangular in shape and is enclosed in a plastic enclosure.
This type of antenna can be manufactured in a standard printed circuit board methods. Patch antennas are mostly used to be semi-directional; Whereas a patch antenna has a beamwidth between 30 to 180 degrees and a typical gain of 9 dB.
Sector antennas are also another type of semi-directional antenna. Sector antennas provide a pie-shaped (sector) radiation pattern and are usually installed in a sectorized array.
Their beam width is between 60 to 180 degrees, in which 120 degrees is very typical. In a sectorized array, antennas are mounted back-to-back to provide full 360-degree coverage. Sector antennas are used extensively in cellular communication.
A very commonly used directional antenna is the Yagi-Uda Array , also known as Yagi. It was invented by Shintaro Uda and his colleague, Hidetsugu Yagi , in 1926 .
A Yagi antenna uses several elements to form a directional array. A single driven element, typically a dipole, propagates RF energy; The elements that are placed are immediately driven in front of and behind the element so that it can re-radiate RF energy in phase and out of phase, as well as enhance and retard signals respectively.
These elements are called parasitic elements.
The elements which come behind the element driven element are called reflector, whereas the elements which come in front of the driven element are called directors. Yagi antennas have beamwidths in the 30 to 80 degrees and provide well excess of 10 dBi passive gain .
Parabolic या Dish Antenna
Parabolic, or dish, antennas are a very familiar type of directional antenna. A parabola is a symmetric curve; A parabolic reflector is a surface that can provide a 360-degree rotation throughout a curve — this dish is technically called a paraboloid. A parabolic reflector has a high degree of directivity and has the ability to focus RF energy into a beam, like a flashlight.
Parabolic antennas have a very narrow beamwidth, usually no more than 25 degrees. Gain depends on diameter and frequency; As in 2.4 GHz, a 1-meter dish provides a gain of about 26 dBi, while a 10-meter antenna provides a gain of 46 dBi in the same frequency. This antenna is “fed” with a half-wave dipole antenna or a feed horn.
Parabolic antennas are used for long distance communication links between buildings or in large geographic areas. Very large parabolic antennas are used for radio astronomy and can provide a gain of 10 million or about 70 dBi.
A variation of the dish is called a grid antenna. Since a parabolic reflector is very easily heeled out of place and their alignment deforms even in moderate wind conditions. Therefore to prevent this problem, the reflector is perforated in a grid.
The spacing of grid elements is frequency dependent; And it is inversely proportional to the frequency. Its gain and beamwidth are similar to that of a parabolic antenna.
how antenna works
You would love to know how this Antenna works. Suppose you are in charge of a radio station and you want to transmit your program to the outside world. How are you going to do this?
For this, you may use microphones that capture your voice and convert them into electrical energy. You can take that electricity and then use it to send it out to a tall metal antenna.
While this antenna will boost it many times so that it will be able to travel farther, the more you boost this signal, the more distance it will be able to cover. Since these electrons (tiny particles within atoms) move back and forth in an electric current along the antenna, this produces invisible electromagnetic radiation in the form of radio waves.
These waves, which are partly electric and partly magnetic, travel at the speed of light, and they carry radio programs with them. What happens when a person turns on the radio in his house which is kilometers away from that station?
These are radio waves that you send through a metal antenna that force electrons to wiggle back and forth. It generates an electric current — it transmits the signal to the electronic components (receiver) of the radio in your home and converts that signal back into the sound that you hear.
Transmitter and receiver antennas have very similar designs. Where antennas are used to send signals, they are very big and bulky in radio or TV stations, while receivers like you and us who use in homes, these are very big for watching radion channels or tv channels. are only smaller than the senders. But the work of both is same.
Waves are not always zapping in the air when they are sent from transmitter to receiver. It depends what kind of waves we are sending, what is their frequency, how far we want to send it, and what we want to do with these waves etc. :- Mainly three different types of ways From which the waves travel :-
1. The first is “ Line of Sight ”, it was used many years ago. In this the waves were sent in a single direction like a beam of light. They were used in old-fashioned long-distance telephone networks, in which microwaves were used to carry calls between large high-end communication towers. But this technology was completely stopped due to the use of fiber-optic cables.
2. Then there is Ground Wave . These waves can travel around the Earth’s curvature. AM (medium-wave) radio travels in this way for short-to-moderate distances . This explains why we hear radio signals even when we do not see any radio transmitter in front of our eyes.
3. Finally comes the “ Ionospheric Wave ”. In this, waves are shot (sent) into the sky, and they
Reflecting from the ionosphere, it bounces off, and then reaches the ground again. These ionospheres are an electrically charged part of the Earth’s upper atmosphere that reflects the waves.
But they work better at night because at that time they reflect all the waves in the ionosphere, while during the day they absorb some waves. Due to this property of the ionosphere, it is also called Sky Mirror and radio waves can be sent to very long distances.
What are some important features of antennas?
Although Antenna has many features, but here we will talk about some important features only.
Dipoles are very directional: so they can only pick up signals that come in right angles towards them. That’s why it is very important to mount a TV antenna properly in your home that too in the right way and in the right direction. Admittedly, highly directional antennas do look a bit odd and they are also a bit difficult to install, but if they are properly aligned then they also have very little interference and no unnecessary signals.
The gain of an antenna means how much it can boost the signal. Many times you must have seen that TVs often catch some bad signal without any antenna.
This is because its metal case and other components act like a basic antenna, and are not focused in any particular direction, and therefore capture the signals near it. You can get better gain by using a proper directional antenna.
Gain is measured in decibels (dB). One thing must be understood today that the higher the gain, the better the reception will be. That’s why outdoor antennas work better than indoor because they have more gain.
The bandwidth of an antenna is its range of frequencies (or wavelengths, if you prefer it) over which it works effectively. The broader the bandwidth, the greater is its range and the more different radio waves it can pick up.
This is more helpful for television, where you can pick many channels. Whereas Mobile, Radio has a narrow bandwith.
Aperture is also called effective aperture of the antenna and it actively participates in transmission and reception of electromagnetic waves. All that is received by the power antenna is associated with the collective area in one place. This collected area is called the effective aperture of an antenna.
An electromagnetic wave launched from an antenna can be polarized both vertically and horizontally. If a wave is polarized in the vertical direction, then the E vector is vertical and requires a vertical antenna.
Whereas if the vector E is horizontal, then it needs a horizontal antenna to launch. Sometimes circular polarization is also used, it is a combination of both horizontal and vertical ways.
Effective length is a parameter of antennas that characterizes the efficiency of the antenna as to how antennas transmit and receive electromagnetic waves. Effective length is defined for both transmitting and receiving antennas.
The ratio of the intensity of the electric field produced in the antenna to the EMF receiver input is called the receivers’ effective length. The effective length of the transmitter is called the length of the free space of the conductor and the current distribution across its length when it generates the same field intensity in any direction of radiation.
Effective Length = (Area under non-uniform current distrbution)/(Area under uniform current distribution)
This is a very important property in an antenna called radiation pattern or polar diagram. In the case of a transmitting antenna, there is a plot that discusses the strength of the power field radiated by the antenna in various angular directions.
A plot is obtained for both vertical and horizontal planes – and these are called vertical and horizontal patterns, respectively.
Advantages of Antennas According to Their Types
Let us know about the advantages of Antennas. By the way, these advantages depend on the types of antennas. Let’s know.
Dipole Antenna : These are cheap and exhibit good gains . Whip Antenna : It also
delivers good performance due to its smaller size as compared to dipole antenna. ➨ Loop Antenna with: These are and are not easily tuned to de-cheap hand movements. ➨ Spiral Antenna : There is not much compared to their size whip antenna. They are used more for wideband applications. Helical Antenna : It is very directive antenna and it provides good amount of gain. ➨ Microstrip Antenna
: These are very simple and chip antenna. They are used in smartphones because their structure is very thin.
➨ Ceramic Antenna : These are very much smaller size and are not much affected by the environments factors. In these separate components are used.
➨ Slot Antenna : their design is very simple and consists of small size. They are of more robust nature.
DisAdvantages of Antennas According to Their Types
Let us know about the diadvantages of Antennas. By the way, these disadvantages depend on the types of antennas. Let’s know.
➨ Dipole Antenna: These large size exhibit a lower frequency.
➨ Whip Antenna: These are very much costly. In these, a better ground plane is needed to get good performance.
➨ Loop Antenna: They are very poor gain, it is difficult to tune and are very narrowband. Spiral Antenna : The major disadvantage of this is that it is very difficult to feed these
types of antennas. Helical Antenna: They are very bulky in size. They can be de-tuned very easily from nearby objects. That’s why there are more disturbances in it. ➨ Microstrip Antenna
: They are of very large size in the lower frequency. PCB design can affect their performance and tuning. It is very difficult to design it for less than 433 MHz.
➨ Ceramic Antenna: These are very much cost. Also, they deliver only medium performance. These are the matching function of PCB size and ground plane shape.
➨ Slot Antenna: Their size is very large there is lower in frequency and are therefore very difficult to have less than 433 MHz of which the lower frequencies to design.
What are the applications of Antenna?
Antennas have many different applications, which differ according to the types of antenna and their application is also different. Let us know about some important applications.
- They are mainly used for radio broadcasting.
- It is also used in navigation systems by the sailors of ships.
- For radio transmission and reception.
- It is also used to see the direction in GPS.
- For satellite communication.
- Also, they are also used for radio frequency identification.
What is the future of Antennas:
Although antennas are generally considered to be an antiquated technology, telecommunications companies are always in search of how they can further innovate these antennas so that they can be used in the next generation of electronics.
As of now, product engineers are using 3D printing and refined manufacturing techniques to make antennas smaller, lighter, and more powerful than ever before.
Cell phone companies are working on bringing forward 5G technology, which is going to bring a big revolution in the era of small cell towers. Similarly, further, we can get to see more such technologies, using which the entire body of Antennas can be changed.
But one thing is, no matter how many innovations happen, traditional cell phone towers and larger antennas have played a very important role for us and in shaping our communication system and will continue to do so in the times to come.