The antenna is a device that helps to send and receive signals to represent data. Germans invented the first antenna in 1888. This antenna was used for wireless communication. As time passed, different kinds of antennas were invented based on aperture, reflector, aperture, log periodic, and wire.
In this blog, we will talk about a Dipole Antenna, its design, application, working, and various types. We will also discuss many other things related to a dipole antenna and how it works in different applications.
What is Dipole Antenna?
Dipole antenna is also known as dipole aerial or doublet. It is a kind of Radio Frequency antenna containing 2 conductive elements namely rides or wires. It is an antenna that generates a radiation pattern similar to an elementary electric dipole.
Dipole antennas are very common kinds of antennas used in various applications. They are simple to use for everyone. The term dipole means “Two poles” and it contains two similar elements like wire or rods. The length of a metal wire is about half of the maximum wavelength. In the center of the dipole antenna, the conductive materials are separated via an insulator known as an antenna section.
The RF voltage source is provided in the center of the antenna. Then the voltage and current passing through these 2 conductive elements produce electromagnetic or radio signals. These signals are then sent outside the antenna.
“The voltage in the center of the dipole antenna is minimum while the current is maximum. On the other hand, the current is minimum and the voltage is maximum at both ends of the antenna.”
Dipole Antenna Design
After discussing the dipole antenna in the above section, we will further discuss the design of a dipole antenna. This antenna mainly includes 2 conductive elements such as wires and rods. It may also contain a wire where the feeder at both the center and radiating sections are on one side.
In a log periodic dipole antenna, the length of a metal wire is half of the highest wavelength. The conductive element in a Military Dipole Antenna is divided in the middle into 2 sections via an insulator known as an antenna section. These sections are connected to a feeder or coaxial cable in the center of an antenna.
The radiating element length depends on various factors of an antenna such as feed impedance, center operating frequency, and so on. In the case of a dipole antenna, the length is the most important factor.
Dipole Antenna Transmitter
The dipole antenna produces the radio waves in the transmitter section. The voltage at a particular frequency is provided to the antenna. The voltage will pass through the various elements of the antenna and the current flow will produce magnetic and electric waves.
In an antenna, the transmitter is the main element that is made with a conductor. The conductor takes an electric current where the intensity of the current will change into RF radiations that travel in space.
Dipole Antenna Receiver
In the receiver section of the dipole antenna, the electromagnetic waves passing through the antenna will produce a little voltage. This voltage makes the antenna a source of signal for the receiver’s input.
The receiver of a dipole antenna works opposite to that of a transmitter. It gets RF radiation and converts in into electric currents in an electric circuit that is connected to the antenna.
How Does the Dipole Antenna Work?
RF voltage source is applied to the center of the 2 sections of a dipole antenna. The flow of voltage and current through the two conductive elements can produce radio or electromagnetic waves that radiate outside the antenna.
Voltage is minimum and the current is maximum in the center of the dipole antenna. Contrary to that, the voltage is maximum and current is minimum at both the ends of the antenna.
Different Types of Dipole Antenna
The different Types of Dipole antenna depends on different factors. Let us have a look at the various types of a dipole antenna:
1. Folded Dipole Antenna
Collection of a two-dipole antenna that is connected separately to make a thin wire loop is called as a folded dipole antenna. This antenna is folded back and contains 2 half-wave dipoles where one dipole is continuous and the other is divided in the middle of antenna. These dipoles are folded and connected in parallel at the two ends.
The radiation pattern of a folded dipole antenna is similar to a normal dipole except few things. This antenna has higher input impedance and bi-directional directivity. Normally, a folded dipole antenna comes in 2 types namely two-wire and three-wire.
2. FM Dipole Antenna
FM dipole antenna is easy to use and it is available at low cost. These antennas are perfect in the roof space in an internal FM antenna. FM dipole antennas can be used after using a temporary antenna. They are half-wave half dipole vertically polarized antennas which are used often to offer better reception of VHF FM broadcast. These dipole antennas are used for FM broadcasting where the frequency ranges between 88 MHz and 108 MHz.
3. Fan Dipole Antenna
Fan dipole antenna is a multi-band wire antenna and has a simple design. It contains numerous dipole antennas that share a similar coaxial feed line. Some nearby elements in an antenna can interfere with each other and are tightly held. Mechanical design of an antenna is not critical as it can be arranged as an inverted V shape in a horizontal manner.
4. Half-wave dipole antenna
In this dipole antenna, the length of a dipole is half the wavelength at the operating frequency. It has a simple resonance structure as compared to other antennas. Half-wave dipole antenna has an operating frequency between 3 kHz and 300 GHz. This antenna is lightweight and cost-effective.
This is all about a dipole antenna, its design, working and various types. A Military Coaxial Dipole Antenna is used in radio and telecommunications for transmitting and receiving signals. These antennas are widely used in TV and radio receivers.