In this modern world, many engineers are becoming increasingly interested in specializing in communication fields, specifically in wireless communication.

However, this entails a basic knowledge of fundamental communications, including electromagnetic radiation, different types of antennas, and various phenomena associated with propagation, among other topics.

Antennas play a crucial role in wireless communications, as they are responsible for converting electronic signals into electromagnetic waves. They are considered fundamental components of electrical circuits because they connect the transmitter to the free space and the receiver. Here, we are going to focus on the properties of antennas.

What is an Antenna?

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An antenna refers to a structure installed for the purpose of capturing or transmitting radio electromagnetic signals. They come in various shapes and sizes. The most common antennas are small-sized ones usually installed on roofs for watching television, while larger ones are designed to capture signals from satellites.

SCaN (Space Communications and Navigation) antennas come with a bowl-shaped design that focuses directly on signals at a specific point, also referred to as a parabolic antenna. This type of antenna can both capture and transmit electromagnetic signals. They can move horizontally and vertically to capture and transmit signals.

The process starts at a transmission line, where a signal is passed on to an antenna. This signal is then transformed into electromagnetic energy and spread throughout space. Often, an electrical device such as an antenna is used to convert electrical power to electromagnetic signals and vice versa. Ultimately, antennas play a significant role in transmitting and capturing electromagnetic radiation.

The transmitting antenna receives electrical signals originating from a transmission line and converts them into radio waves. Conversely, the receiving antenna accepts radio signals from space, converts them into electrical signals, and sends them to a transmission line. Some basic antenna parameters include gain, bandwidth, radiation pattern, impedance, polarization, and beamwidth.

Why Are Antennas Essential?

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There are several reasons why antennas are essential, but the major reason is that they offer an efficient means of transmitting signals that other techniques cannot achieve.

For example, pilots of airplanes often need to communicate with ATC personnel. Fortunately, wireless communication and antennas facilitate this communication.

What Are the Different Fundamental Parameters of Antennas?

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It is a fact that an antenna plays an essential role in a wireless communication system. Hence, it is important to understand that the characteristics of a wireless communication system greatly depend on the characteristics of the antenna being utilized within the system.

For example, the operational characteristics of the communication system will depend on its origins, which are the directional characteristics of the antenna. In most cases, antennas have fundamental parameters, also referred to as properties or characteristics of the antenna. The following are some of the basic characteristics of an antenna:

  • Polarization of antenna
  • Radiation pattern of antenna
  • Intensity of radiation
  • Gain and directivity
  • Effective aperture
  • Bandwidth
  • Effective length
  • Power gain and radiation efficiency
  • Input impedance

What are the Properties of Antennas?

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The following are some of the various properties of antennas:

Aperture

The aperture plays an important role in transmitting and receiving electromagnetic waves. The power obtained by the antenna gets involved in the collective area of an antenna, also called the effective aperture.

Antenna Gain

This parameter is responsible for measuring the level of directivity of the radial pattern of the antenna, also referred to as the gain. If an antenna has a higher gain, then its radiation pattern is more effective. Antennas are created in such a way that their power diminishes in unwanted directions and increases in the desired direction.

Directivity and Bandwidth

When it comes to the directive of an antenna, it refers to the degree of concentrated power radiation in a certain direction. It can also refer to the ability of an antenna to send radiated power in a particular direction.

When choosing an antenna, one of the most important parameters is the bandwidth. It refers to the range of frequencies within which an antenna is capable of properly radiating and receiving energy.

Effective Length

Effective length measures the efficiency of an antenna when it comes to the transmission and reception of electromagnetic waves. This parameter of an antenna can be applied to both receiving and transmitting antennas. The effective length of the transmitter refers to the extent of the free space in a conductor, as well as the present distribution across its length.

Polarization

The electromagnetic wave that comes from an antenna might be polarized horizontally and vertically. In case the wave is polarized vertically, the E vector is also vertical, and a vertical antenna is needed.

On the other hand, if the wave is polarized horizontally, then it follows that the vector E is also horizontal, and a horizontal antenna will be needed for launching it. Most often, a combination of both vertical and horizontal ways is used, also known as circular polarization.

Polar Diagram

A polar diagram or radiation pattern is considered the most vital property of an antenna. When it comes to the transmitting antenna, it refers to the degree of the power field generated by the antenna in different angular directions.

What are the Different Types of Antennas?

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After covering the properties of antennas, we will now explore the different types of antennas and how they can be useful in various applications.

Log Periodic Antennas

Also known as a log-periodic array, a log-periodic antenna is a multi-element, directional antenna with a narrow beam that can be used for a wide range of frequencies.

In this type of antenna, you can find a series of dipoles installed along the antenna axis at various space intervals of time followed by a logarithmic function of frequency. It is utilized in a wide variety of applications wherein its variable bandwidth is needed together with its directivity and antenna gain.

Bow-Tie Antennas

Also referred to as a Butterfly antenna or Biconical antenna, a bow-tie antenna is an omnidirectional antenna with a wide band. Based on the size of this antenna, it serves as a high-pass filter with a low-frequency response.

Hence, if the frequency reaches its maximum limits and deviates from the design frequency, there is a tendency for the antenna’s radiation pattern to get distorted and dispersed. Since the bow-tie antenna is a planar, it is known as a directional antenna.

Log-Periodic Dipole Array

Log-periodic dipole array is one of the most popular types of antenna utilized in wireless communication technology. Basically, it includes several dipole elements.

The size of these dipole-array antennas decreases from the back end to the front end. The major beam of this RF antenna originates from the smaller front end. At the back end of the array, the element is large with the half-wavelength running in a low-frequency range.

However, as the array runs towards the front end, the spacing of the element decreases. When the operation starts, the frequency differs, and an efficient transition occurs along the array of the elements, as a result, an active region is formed.

Wire Antennas

Commonly known as curved or linear antennas, wire antennas are cheap, simple, and versatile since they can be used in a wide variety of applications. Furthermore, wire antennas are subdivided into four categories:

  • Short Dipole Antenna: Among the different types of antenna, short-dipole antenna is the simplest. It is an open-circuited wire which prioritizes the size of the wire in relation to the wavelength of the frequency.
  • Dipole Antenna: A straightforward antenna that includes two thin metal rods and at the center is a sinusoidal voltage difference.
  • Monopole Antenna: Half of a dipole antenna is a monopole antenna.
  • Loop Antenna: It has the same characteristics with both monopole and dipole antennas since they are simple and easy to make.

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