Wireless Communication In today’s modern age, many engineers are showing interest in specializing in the field of communication. But this requires a basic knowledge of the basic communication concepts such as the type of antenna, electromagnetic radiation, and various events related to transmission, etc.
Antennas play a major role in the case of wireless communication systems as the antenna effectively converts electromagnetic waves to electronic signals. Antennas are the basic components of any electrical circuit. Because it provides interconnecting links between transmitter and free space or free space and receiver.
Before discussing the type of antenna, there are some properties that should be known. So today we will see in today’s article what an antenna is. And let’s talk about an overview of its type.
What is an Antenna?
Definition: A metallic structure used to transmit and capture a radio electromagnetic signal is known as an antenna. These are available in different sizes as well as shapes. Smaller antennas were used to watch television in the past. While large antennas are used to capture the signal from the satellite.
SCAN (Space Communications and Navigation) Such antennas consist primarily of a bowl-shaped antenna with a special antenna that captures the signal at a specific end called the parabolic antenna. This type of antenna allows both transmission and capture of the electromagnet signal. Which can be moved horizontally and vertically to transmit and capture the signal.
The signal is given to the antenna by the transmission line. This signal can then be converted into electromagnetic energy to be transmitted into space. Sometimes an electrical device such as an antenna or aerial is used to change the electromagnetic signal and vice versa the electrical power. Antennas play an important role in transmitting electromagnetic radiation.
In a transmitting antenna, an antenna receives an electrical signal from a transmission line and converts it into a radio wave. Receiving antennas is the exact opposite as it allows radio signals from space and converts them into electrical signals and provides them in the transmission line. Typical antenna parameters are bandwidth, gain, radiation pattern, polarization, impedance, and beamwidth.
Why do we need Antennas?
Antennas are used for many reasons but the main reason for this is that it provides a simple method to transmit the signal where other types of techniques are not possible.
For example, the pilot of an aircraft often needs to communicate with ATC i.e. air traffic control. So this communication between them can be done through wireless communication and antenna which is the entrance for it. Therefore, there are many conditions otherwise there are applications where the cable is selected on the wireless communication through the antenna.
Fundamental Parameters of Types of Antennas:
Antennas play an important role in any wireless system. So the thing to know is that the wireless communication features are based on the feature of the antenna that is used inside the system.
For example, the operational characteristics of a communication system will trace its origin in the directional characteristics of the antenna. Antennas In many applications the antenna is associated with some basic parameters. Sometimes it is called the features or properties of the antenna. Some of the features of the antenna are as follows.
- The radiation pattern of the antenna.
- The intensity of radiation.
- Benefit and direction.
- Effective aperture.
- Power gain and radiation efficiency.
- Effective length.
- Input constraint.
- Polarization of the antenna.
Properties of Types of Antennas:
The various properties of antennas are as follows:
|Sr.No||Properties of Types of Antennas|
|#3.||Directivity and Bandwidth|
#1. Antenna Gain:
An antenna that measures the degree of directionality of a radial pattern is known as a parameter gain. The antenna is more effective with more advantages in its radiation pattern. The antenna is designed in such a way that the power increases in the desired direction and decreases in the unwanted directions.
G = (Power Radiated by an Antenna)/(Power Radiated by Reference Antenna)
This aperture is also known as the effective aperture of the antenna. Which actively participates in the transmission and reception of electromagnet waves. The power received by the antenna is associated with the mass field. This collected area of the antenna is known as the effective aperture.
Pr = Pd * A watts
A = pr / pd m2
#3. Directivity and Bandwidth:
The direction of the antenna is lectured as a measure of the power radiation concentrated in a particular direction. It can be thought of as the ability of an antenna to direct radiant power in a given direction. The average radiation intensity can be recorded as the ratio of the radiation intensity in a given direction.
Bandwidth is one of the desired parameters when choosing an antenna. It can be defined as a range of frequencies. On which the antenna can properly transmit and receive energy.
An electromagnet wave initiated by an antenna can be polarized vertically and horizontally. If the wave is polarized in the vertical direction then the E vector is vertical and it needs a vertical antenna. If the E vector is horizontal then it needs a horizontal antenna to start. Sometimes circular polarization is used, it is a combination of both horizontal and vertical.
#5. Effective length:
Effective length is the dimension of the antenna that indicates the efficiency of the antenna in transmitting and receiving the electromagnet wave. The effective length for the antenna to transmit and receive can be defined.
The ratio of EMF to receiver input for the intensity of the electric field on the antenna is known as the effective length of the receivers. The effective length of the transmitter can be defined as the length of the empty space of the conductor. The current distribution in its length produces the same field intensity in any direction of radiation.
Effective Length = (Area Under Non-Uniform Current Distribution)/(Area Under Uniform Current Distribution)
#6. Polar Diagram:
The most important property of an antenna is its radiation pattern or polar diagram. This is a plot in the case of a transmitting antenna. Which discusses the strength of the power field propagated by the antenna in different angular directions. Whose figure is as follows. A plot can also be obtained for both vertical and horizontal planes. And it is also named as a vertical and horizontal pattern.
Different Types of Antennas:
So far we have covered the properties of antennas, now we will discuss in detail the different types of antennas. Antennas are used in various applications.
The different types of antennas are as follows:
#1. Log Periodic Antennas.
- Bow Tie Antennas.
- Log-Periodic Dipole Array.
#2. Wire Antennas.
- Short Dipole Antenna.
- Dipole Antenna.
- Monopole Antenna.
- Loop Antenna.
#3. Travelling Wave Antennas.
- Helical Antennas.
- Yagi-Uda Antennas.
#4. Microwave Antennas.
- Rectangular Microstrip Antennas.
- Planar Inverted-F Antennas.
#5. Reflector Antennas.
- Corner Reflector.
- Parabolic Reflector.
#1. Log-Periodic Antennas:
Another name for Log-Periodic Antennas is Log-Periodic Array. This antenna is a multi-element, directional narrow beam antenna. Which operates on a wide range of frequencies.
This is made up of a series of dipoles placed along the antenna axis at different space intervals of time by the logarithmic function of the antenna frequency. These antennas are used in a wide range of applications. Where variable bandwidth with antenna gain and directivity is required.
#1.1. Bow-Tie Antennas:
This type of antenna is also known as Biconical antenna or butterfly antenna. Biconical antennas are ubiquitous wide-band antennas. This antenna has a low-frequency response according to its size. And this acts as a high pass filter. As it reaches its upper limit, the radiation pattern of the antenna away from the design frequency becomes distorted and diffuses.
Most bow tie antennas are biconical antenna derivatives. Discon is a type of semi-biconical antenna. A bow-tie antenna is a planar, and therefore, a directional antenna.
#1.2.Log-Periodic Dipole Array:
The most common type of antenna used in wireless communication technology is a log-periodical dipole array. Which basically consists of several bipolar elements. This bipolar array reduces the size of the antenna from the rear end to the front end. The main beam of this RF antenna comes from a small front end.
The rear end element of the array is larger in size with half-wavelengths operating in the low-frequency range. The distance of the element decreases towards the front end of the array. Which includes small arrays. The frequency varies during this operation. A smooth transition occurs with an array of elements, leading to the formation of an active field.
#2. Wire Antennas:
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This antenna is also known as a linear or curved antenna. These antennas are very easy to use, cheap, and are used in large quantities. These antennas are classified into four other types as follows.
The details of which are as follows.
- Short Dipole Antenna.
- Dipole Antenna.
- Monopole Antenna.
- Loop Antenna.
#2.1. Short Dipole Antenna:
This type of antenna is a simpler type of antenna than all types of antenna. This antenna has an open rotating wire. In which the short indicates “relative to the wavelength”. Therefore this antenna prefers the size of the wire relative to the wavelength of the frequency of operation.
It makes no consideration about the full size of the dipole antenna. The short dipole antenna is made up of two co-linear conductors. Which is a small distance between the conductor through the feeder. The dipole is considered short if the length of the radiating element is less than one-tenth of the wavelength.
Short dipole antennas are made up of two co-linear conductors. Which is a small distance between the conductor through the feeder.
Short dipole antennas are seldom satisfactory from a performance standpoint. This is because most of the power entering the antenna is depleted in the form of heat and the resistance loss is also gradually increasing.
#2.2. Dipole Antenna:
Dipole antennas are one of the most straightforward antenna configurations. This Dipole antenna consists of two thin metal rods with a sinusoidal voltage difference between them. The lengths of rods are chosen in such a way that they have a quarter length of wavelength at operational frequencies.
These antennas are used in the design of their own antennas or other antennas. It is very easy to build and use. Dipole Antenna has two metallic rods through which current and frequency flow. This current and voltage flow create an electromagnetic wave and the radio signals are red.
The antenna contains a radiating element that splits the rods. And takes it from the receiver using the feeder on the transmitter. It creates currents through the center. Different types of dipole antennas used as RF antennas include semi-wave, multiple, fold, non-resonant, and so on.
#2.3. Monopole Antenna:
A monopole antenna is half of a normal Dipole antenna located on a ground plane whose diagram is as follows.
The radiation pattern above the ground plane will be similar to that of a half-wave dipole antenna. However, the total power developed is half that of a Dipole Antenna. This region extends only to the region of the upper hemisphere. The directivity of this antenna doubles compared to Dipole Antenna.
These antennas are also used as vehicle mounting antennas. As they provide the ground plane required for the antennas on the ground.
#2.4. Loop Antenna:
Loop Antenna shares a similar characteristic with both Dipole and Monopole antennas. As it is simple and easy to build. Loop Antenna is available in various shapes such as circular, elliptical, rectangular, etc. The basic characteristic of a loop antenna is independent of its shape. This is widely used in communication links with a frequency of about 3 GHz.
These antennas are also used as electromagnetic field probes in microwave bands. The circumference of the loop antenna determines the efficiency of the antenna. Dipole and monopole antennas are similar. These antennas are further classified into two types. Electrically small and electrically large depending on the circumference of the loop.
Electrically small loop antenna———> Circumference≤λ⁄10
Electrically large loop antenna ———> Circumference≈λ
Single turn electrically small loops have smaller radiation resistance compared to their loss resistance. Smaller loop antennas can be improved by adding more turns to the radiation resistance. Multi-turn loops have higher radiation resistance, even if they have lower efficiency.
Because of this small loop antennas are mostly used to receive antennas where loss is not mandatory. Small loops are not used to transmit antennas due to their low efficiency.
Resonance loop antennas are larger in proportion. And is guided by the operation of the wavelength. They are also known as large loop antennas. Because they are used on higher frequencies such as VHF and UHF, in which their size is convenient.
They can also be seen as fold-dipole antennas. And can be distorted into various shapes like round, square, etc. And have similar characteristics as high radiation efficiency.
#3. Travelling Wave Antennas:
Travelling Wave Antennas are classified into different types which are discussed in detail below.
#3.1. Helical Antennas:
Another name for helical antennas is helix antennas. It has a simple structure in the proportions of one, two, or more wires on each wound to form a helix. Usually supported by a ground plane or shaped reflector and run through the appropriate feed. The most common design of this is a wire that is supported by the ground and fed from a coaxial line.
The radiation properties of helical antennas, in general, are associated with this specification. The electrical size of the structure in which the input impedance is more sensitive to the pitch and the size of the wire.
Helical antennas have two main radiation modes: normal position and axial position. Axial mode is used in a wide range of applications. In normal conditions, the dimensions of the helix are smaller than its wavelength. These antennas act as short dipole or monopole antennas. In the axial position, the dimensions of the helix are the same as its wavelength. This antenna acts as a directional antenna.
#3.2. Yagi-Uda Antennas:
Another antenna that uses passive elements is the Yagi-Uda antenna. This type of antenna is affordable and effective. It can be made up of one or more reflective elements and one more directing element.
The Yagi antenna can be mounted for horizontal polarization in the forward direction using an antenna with a reflector-driven fold-dipole active element and directors.
#4. Microwave Antennas:
Microwave Antennas to Antennas Working on Microwave Frequencies Known as. These antennas are used in a wide range of applications.
#4.1. Rectangular Microstrip Antennas:
Low-profile antennas are selected for spacecraft or aircraft applications based on specifications such as size, weight, cost, operation, ease of installation, etc. Such antennas are known as rectangular microstrip antennas or patch antennas. They just need space for the feed line. Which is usually placed behind the ground plane.
The disadvantage of such antennas is that they are inefficient and have very narrow bandwidth. Which is usually a fraction of a percent or a few percent at most.
#4.2. Planar Inverted-F Antennas:
Planar Inverted-F Antennas can be considered as a type of linear inverted F antenna (IFA). In which the wire radiating element is replaced by a plate to increase the bandwidth. The advantage of such antennas is that they can be hidden in the housing of the mobile when compared to different types of antennas such as whip, rod or helical antenna, etc.
Another advantage of these antennas is that they absorb power and reduce the back rays from the top of the antenna, which increases efficiency. Its high advantage in both horizontal and vertical positions. This feature remains the most important for any type of antenna used in wireless communication.
#5. Reflector Antennas:
Reflector Antennas are classified into two types which are further discussed below.
#5.1. Corner Reflector Antenna:
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An antenna that consists of one or more dipole elements placed in front of an angled reflector. That one angle is known as Corner Reflector Antenna. The direction of the antenna can be increased by using this reflector. In the case of a wire antenna, a conducting sheet is used behind the antenna to direct the radiation forward.
The radiating surface of a parabolic antenna has a much larger dimension than its wavelength. Geometric optics based on rays and wavefront are used to find out some of the features of this antenna. Some of the important properties of these antennas can be applied using ray optics and other antennas using electromagnetic field theory.
One of the useful properties of this antenna is that it converts the diverging spherical wavefront into a parallel wavefront which produces a narrow beam of the antenna. Different types of feeds use this parabolic reflector. These include horn feeds, Cartesian feeds, and bipolar feeds.
Types of Antennas Used in Mobile Communications:
Two types of antennas are used in mobile communication. Such as rectangular and cellular. These antennas offer a wide variety of services. As the rectangular type serves in the region of the near while the circular type is used for the communication of inter BTS.
This type of antenna is a directional indicator antenna that is used to provide an external area around the mobile tower. These types of antennas are mainly connected to BTS using co-axial cables. Used to transmit or receive data at close range via mobile phone. In general, these antennas support all types of RF spectrum. Used in various network services such as 2G or 3G, or 4G services.
This type of antenna is used exclusively for communication between BTS. This type of antenna operates at microwave frequencies. And that includes point-to-point transmission or reception. These antennas are connected by means of waveguides which will terminate at BTS. And from there the data can be transmitted to the outdoor antenna unit or in the area closer to the claim on the IBS.
Radiation Patterns of Different Types of Antennas:
The energy emitted through the antenna can be represented by the radiation pattern of the antenna. The function of this direction is the representation of the figure for the distribution of radiation energy in such a space.
In the radiation pattern diagram of the antenna, the radiating energy can be accurately indicated by illustrated patterns. In it, the arrow indicates the direction of radiation. These patterns are power or field patterns.
The power pattern is designed as a function for the intensity of different fields. These are usually designed on a logarithmic scale on the DB scale. The structures of different antennas form radiation patterns and their complexity depends mainly on the composition of the antenna.
Field patterns can be formed in the same way as fieldwork. They are designed on a logarithmic scale.
Radiation patterns are available in different types from below.
- Shaped beams.
- Omni-directional or non-directional pattern.
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