An antenna is a device that can convert alternating current into electromagnetic waves and vice versa. The current and the electromagnetic waves must be time-varying to carry information. Antennas were discovered back in 1888 by Heinrich Hertz. He created and used antennas to prove that electromagnetic waves exist. They are used in a wide variety of applications in electronic devices, mainly for military, medical, and civil applications. With the help of antennas, you can send and receive radio transmissions. Many technologies like mobile phones, radio, TV, global positioning systems, connected cars, radars, space communications, and many more would not have been possible without antennas. Therefore, we can tell how important they are and how much they are used in industries for various applications.
How do Antennas Work?
The simplest and the most common antenna that has been used for a long time is the dipole antenna. The dipole antenna is simply one that has two wires which are equal in length and are connected to a transmitter or a receiver on one side. When the antenna is supplied with an alternating voltage, the oscillation of electric charges along the wire begins, and then they shift between negative and positive with time.
Both the electric charges and the electrons responsible for carrying these charges generate electric and magnetic waves capable of carrying signals and information through the air at the speed of light.
The frequency of the dipole antenna is determined by the number of times per second that the charged electrons change their polarity along the antenna wire. The frequency of antennas is measured in Hertz, and one Hertz equals one oscillation in one second. For example, the polarity of a Wi-Fi antenna is changed 2.4 billion times each second. Therefore, its frequency is 24 Gigahertz. The length and size of the antenna are a function of its wavelength and frequency. The lower the frequency, the lower the wavelength, and the larger the antenna will be.
Types of Antennas
There are different types of antennas depending upon their size and functionality. Some of the well-known ones are as follows:
Aperture
This type of antenna has an opening and can radiate energy. The opening of this antenna is known as the aperture. These types of antennas can send and receive signals in all directions. Their radiation is also considered more efficient and significant than the two-wire line. They are primarily used in microwave and search radar applications.
Reflector
These types of antennas have one or more systems containing reflecting surfaces capable of transmitting and absorbing electromagnetic waves. Their main applications are remote sensing and satellite communications. Examples of reflector antennas include corner reflectors and parabolic reflectors.
Yagi-Uda
This is the most commonly known and traditional directional antenna. It has been chiefly used with old home appliances like TV, radios, etc. Many similar elements are arranged linearly in one direction in the Yagi antenna. It can also be used as a bridge in television communication making it more effective.
Applications of Antenna
Antennas are considered central components of the wireless communication system. There are different types of antennas, and each can perform a specific function and has its advantages and disadvantages. Antennas are probably involved in all sorts of communication around you. You will find modern devices being used in search of radars and defense radars. They have been used in more advanced areas of medical research as well.
