
Antenna is a device that receives or transmits radio waves effectively. A helical antenna is a kind of antenna that includes a helical radiating element. This antenna is used at both UHF and VHF frequencies where circular polarization is an important thing. This blog explains the Helical Antenna in detail with its features, benefits, and disadvantages.
What is a Helical Antenna?
A helical antenna is developed with the help of conducting wire-wound in a helical structure form. This antenna is used in ultra-high frequencies. Apart from that, the helical antenna also has some different features such as circular polarization and high gain.
Normally, the frequency range of this antenna is between 30MHz and 3GHz. It is widely used in many applications such as wireless networking, radio astronomy, and satellite communication.
Features of Helical Antenna
We discussed what is helical Antenna in the above section. Now, let us discuss some of the best features of this antenna in the below section:
- This is a simple kind of antenna used for circular polarization.
- If the axial ratio is one in the helical antenna, circular polarization will occur.
- This antenna is used in various bands like UHF and VHF.
- If the axial mode is zero in this antenna, linear horizontal polarization will occur.
- The helical antenna has a simple design and includes maximum directivity.
- This antenna is widely used in axial mode.
- If the axial ratio is infinite in the helical antenna, linear vertical polarization will occur.
Advantages of Helical Antenna
A helical antenna is a very simple antenna that contains a helical radiating element. Now, we will further discuss the major benefits of a helical antenna in the following section:
- A major advantage of a helical Antenna is its simple design and high directivity.
- It has a wide bandwidth and includes a circular polarization.
- Helical antennas have a solid construction and are developed of fine quality materials.
- This antenna is used in both UHF and VHF bands.
- When the antenna uses a circularly polarized pattern, it is acceptable through vertical as well as horizontally polarized antenna types.
- This antenna is normally used in broadband applications because of the wider bandwidth.
Disadvantages of Helical Antenna
Just like benefits, the helical antenna has many disadvantages such as:
- This helical antenna needs more space for installation and set-up.
- It is larger than other kinds of antennas which makes it difficult to use indoors.
- The efficiency of this antenna reduces with the increasing number of turns.
- A helical antenna is expensive and not suitable for users with limited capital.
Design of a Helical Antenna
A helical antenna is developed with the help of conducting wire-like thick copper wire wound in a helical form. It is connected to the ground plate via a feeder line. The simple design of a helical antenna offers waves that are polarized circularly. For this reason, the helical antenna is widely used in various communication-based applications where satellite relays are involved.
Helical antennas operate in 2 modes where the deciding factor is the diameter of the helix and spacing between 2 consecutive spins. The radiation of this antenna depends on the turn spacing, pitch angle, and diameter. The pitch angle is the existing angle between a line tangent to the helix wire and a plane normal to the helix axis.
How Does a Helical Antenna Work?
The current supplies in the conducting wire as the conductive wire in a helical antenna is excited through a coaxial cable or 2-wire transmission line. It causes the field lines generation and emission of radiations. This antenna might emit in various modes. The operation modes of a helical antenna are axial mode and normal mode. Now, let us discuss both the modes in detail in this section:
-
Normal Mode
In the normal mode, both the diameter and pitch of a helical antenna are small as compared to the wavelength. The operation is analogous to the monopole or electrical short dipole. In normal mode radiation, the field of radiation is normal to the helical antenna, and the radiated signals are polarized circularly.
In addition, the normal mode has a narrow bandwidth and low efficiency. Because of these features, the antenna is widely used for UHF TV broadcasting antenna and mobile radios. The radiation pattern in a helical antenna is the combination of short dipole and loop antennas.
The radiation pattern of an antenna in the normal mode depends on the turn spacing and diameter values. However, the normal mode operation is not used often because of a narrow bandwidth and low radiation efficiency.
-
Axial mode
In axial mode, the diameter and pitch of a helical antenna are similar to wavelength. It works similarly to a directional antenna. This mode does not have a simple solution to decide the radiation properties. It is widely used in satellite communication systems and earth-based stations.
Where is a Helical Antenna Mostly Used?
A helical antenna is widely used in many applications such as:
- Satellite and space probe communication because of their circular polarization of the transmitter electromagnetic waves.
- It is used in several satellites such as weather and data relay.
- This helical antenna is used through ballistic missiles for telemetry links.
- It is used at various Earth stations for satellites.
- You can use a helical antenna to receive and transmit VHF signals.
- This antenna is widely used in various communications like space telemetry, space, satellite, and radio astronomy.
- You can establish communication between the Earth and the moon through a helical antenna.
Final Words
This is all about a helical antenna, its features, benefits, and disadvantages. You can get the best helical antenna from the manufacturers online by filling out the online form. Look at the different quotes and compare the prices of the various products.
A helical antenna is available in different sizes as per the needs of the customers. You can choose the affordable antenna for your need from online websites.