Dipole Antenna: Design, Working, and Types

 

The antenna comes in various shapes, materials, and elements. A Dipole antenna is one of the most popular kinds of antennas used in different devices and tools. It is also called a doublet.

In this blog, we will discuss a dipole antenna, its design, types, benefits and disadvantages, and many other things related to a dipole antenna.

What is Dipole Antenna?

A doublet dipole or a Military coaxial dipole antenna is a kind of Radio Frequency antenna including 2 conductive elements like wire or rods. It generates a radiation pattern similar to an elementary electric dipole.

Dipole antennas are widely used for communication and other purposes. It is one of the simplest types of antennas used for transmitting and receiving antennas.

Dipole Antenna Design

The name dipole is 2 poles and this antenna includes 2 same conductive elements like metal wires or rods. The length of a metal wire in this dipole antenna is about half of the maximum wavelength in free space. Feeders at the radiating and center sections of a dipole antenna are on one side. 

The conductive element in the log periodic antenna is divided in the center into 2 sections via an insulator. This portion is called an antenna section. This section is connected to a feeder or coaxial cable in the center of an antenna. Wavelength is the distance between the highest or lowest points.

In addition, the radiating element length can be calculated by several factors like feed impedance and center operating frequency. The length of a dipole is a vital parameter.

Dipole Antenna Transmitter

A dipole antenna produces radio waves at the transmitter section. A high voltage is provided to the antenna at the preferred frequency. Voltage in the antenna elements and current flow will produce magnetic and electric waves.

A transmitter is an important element created with a conductor. This conductor includes electric current when the intensity of the current changes with time and converts into RF radiation that travels in space.

Dipole antenna Receiver

In the receiver portion of the antenna, the electromagnetic waves flowing will produce a little voltage. This will further make the antenna a source of signal for the input of the receiver.

Antenna’s receiver does the reverse operation of the transmitter. It receives RF radiation and converts them into electric currents with the help of an electric circuit that is attached to the antenna.

The working system of a Dipole antenna 

To use a dipole antenna, you need to apply an RF voltage source to the center of 2 sections. This voltage source will produce electromagnetic and radio wave signals to be radiated outside a dipole antenna.

The voltage is minimum and the electric current is maximum in the center of the antenna. On the contrary, the voltage is maximum and the current is minimum at the ends of the antenna.

In short, the dipole antenna converts the signals from RF electromagnetic and emits them at the transmitting end and converts RF electromagnetic signals into electrical signals at the end of the receiver.

Types of Dipole Antenna

Now, we will discuss the different kinds of dipole antennas to understand this concept better. Read below to know the different kinds of a dipole antenna in the below section:

Folded Dipole Antenna

The folded dipole antenna is one of the most popular types. It has 2 dipole antennas that are connected separately to make a thin wire loop. This kind of antenna is folded backwards and contains 2 half-wave dipoles where one is constant and the other is divided at the center part. These dipole antennas are folded together in parallel at both ends of an antenna. 

Short Dipole Antenna

As the name says, this short dipole antenna has a small length in comparison to half a wavelength. It is a kind of simple wire antenna in which there are two ends. One end is open circulated while the other end is fed with an AC source. Usually, the frequency range of a short dipole antenna starts from 3 KHz and ends at 30MHz. This kind of antenna is used in various low-frequency-based receivers.

In a short dipole antenna, the antenna’s length is shorter than the wavelength. The voltage source is connected at one end, and the lines are connected to the other end.

Half-wave Dipole Antenna

The half-wave dipole antenna is a popular kind of antenna wherein the total length is equal to the half-wavelength at the frequency of operation. This antenna is also called a doublet or half-wavelength dipole or Hertz antenna.

There are 2-quarter wavelength conductors with the feed point at the center. This symmetrical antenna has 2 ends connected from equal potential to the center point.

The frequency range of a half-wave dipole antenna starts from 3 KHz and ends at 300 GHz. Many radio receivers use half-wave dipole antennas for clear transmissions.

FM Dipole Antenna

FM dipole antenna is a cost-effective antenna that is very easy to make. Because of affordable cost, these antennas are used widely in roof space in internal FM antenna. The most common task of FM dipole antennas is offering better reception of VHF FM broadcasting. They are used in FM broadcasting and their frequency range starts from 88 MHz and goes up to 108 MHZ.

Fan Dipole Antenna

The fan dipole antenna is also known as a parallel or fanned dipole antenna. It is a kind of multi-band antenna and is easy to design. Fan dipole antenna contains many small dipole antennas with a similar coaxial feed line. When the signal is transmitted, the resonating element is observed through the radio.

You can arrange the mechanical design of a fan dipole antenna in an inverted V shape horizontally. Some arrangements can be made with the help of adjacent spread wires in various directions. In this antenna, some elements interfere with each other because of tight arrangement. 

Advantages of Dipole Antenna

Now, we will discuss the various benefits of a dipole antenna in this section. Some of the major benefits of a dipole antenna are:

·      A dipole antenna is a simple antenna used in radio receivers.

·      Even though the antenna has gaps, these gaps do not affect its performance of the antenna.

·      To get the smooth working of the antenna, you must use a dipole antenna at the resonant frequency.

·      It is easy to design and install a dipole antenna in various configurations such as drooping and inverted V.

·      This antenna will receive the signal from all directions.

·      The antenna gives a radiation pattern of a donut shape.

·      One can reduce a dipole antenna with the help of a loading coil.

Disadvantages of Dipole Antenna

A dipole antenna has some drawbacks such as:

·      Low frequencies might not work in this antenna because of a long wavelength.

·      The antenna will not perform well if the efficiency goes below 27 MHz frequencies when the length of the antenna reduces.

·      Folded type antenna is a complicated kind of antenna. You will need professional guidance to use a folded-type antenna.

·      Outdoor antennas are very bulky. It is difficult to install these bulky antennas from one place to another.

·      Transporting outdoor antennas is difficult because of their heavy weight.

·      A dipole antenna is not efficient as a typical antenna.

·      An indoor dipole antenna is very small in the size.

Where is a dipole antenna used?

A dipole antenna is used for different applications such as:

Ø A dipole antenna can be used in radio receivers and TV.

Ø You can use a dipole antenna with many other simple antennas in different areas.

Ø It can be used for telecommunications and radio.

Ø You can use a dipole antenna either as a transmitter or a receiver.

Ø UHF and VHF antennas are used in different areas such as public communication, coastal areas and land mobile communication.

Final words

This is all about a dipole antenna, its designs, working, benefits, and disadvantages. A dipole antenna is a very popular type of antenna that can be used for TV broadcasting and radio transmission. A Dipole antenna is an affordable antenna used in various areas for gaining solid signals.