In many cases where waves come from a natural source, the fields vibrate in different orientations. Therefore, they are considered unpolarized. Nevertheless, for waves from or through a freely polarizing gadget like an antenna is different. The fields move in a specific direction of propagation. Therefore, they are said to be polarized. The wave polarization concept is hard to understand, but we shall make it easy for you.
Table of Contents
- Basics of Radio Wave Polarization
- How Does Polarizer Work?
- Polarization Categories
- Applications for different types of antenna polarization
Basics of Radio Wave Polarization
A radio wave has one magnetic and one electric field that rotates in a repetitive pattern. Polarization is how the wave moves in a vertical direction. The direction is perpendicular to its movement in a single plane.
When radio waves generate, the magnetic field denoted by B and the electric field represented by the E vector are perpendicular to one another. Also, the radio waves’ direction of motion is vertical. This is to both magnetic and electric fields. Then, the angle between the movement of the radio wave and its oscillation is 90 degrees.
In other words, it occurs in three dimensions. Polarized waves have constant orientation and form a route like the flat plane in space.
How Does Polarizer Work?
A polarizer can be in different ways. First one is a polaroid polarizer. This one comes from a polymer comprising iodine particles. Additionally, the polymer film has a stretch that lines up the polymer on the polarizer.
Therefore, a polarizer rejects any other diffusion of light waves. Besides, it allows the light waves from a given diffusion to go through it. Also, it cleans all beams of light of undefined polarization into a well-defined polarized beam.
What happens if a linear polarized light beam occurs on a polarizer? Let the angle between the diffusion of incident light and the axis of the polarizer be θ. Therefore, the electric field passing on the diffuser is along the route of the diffusion axes.
Different types of electromagnetic wave polarization propagate differently under some circumstances.
In this type of polarization, electric fields move in a linear direction. It is perpendicular to the movement of the axis of the wave. Also, the magnetic field moves in a linear direction. This direction is perpendicular to both the electric field direction and axis motion. Therefore, the diffusion direction is the same as that of the electric field. Within the type, there are several subcategories.
Horizontal polarization: The linear polarization picks up horizontally polarized signals. Then, it radiates them. Therefore, the electromagnetic wave is horizontal with the electric field.
Vertical polarization: The type of linear polarization is unique. This is due to the vertical components within the antenna. It can be a single component. Moreover, the main reason for using vertical polarization is that the antennas have a single component. The component can radiate uniformly around it.
Slant polarization is a type of polarization at an angle to the vertical and horizontal planes. Therefore, both horizontal and vertically diffused antennas can receive the signal.
In circular polarization, the electric and magnetic fields have equal magnitude. Also, the phase change in both vectors is a multiple of 90 degrees. Moreover, there are two types of circular polarization.
Right circular polarization: Polarization is a right circular if both electric field and magnetic field movement coincide clockwise.
Left circular polarization: However, if the coincidence vector of both magnetic and electric fields moves in an anticlockwise direction, the diffusion is left circular polarization.
Circular polarization has several advantages. These are evident in satellite applications. It helps minimize the effects of spin and round reflections. It also reduces propagation anomalies on many satellites. However, circular polarization is challenging to understand. Especially when you compare it to linear polarization. Nevertheless, one can visualize it using a signal spreading from a rotating radio frequency (RF) antenna. Therefore, the tip of the diffusion vector follows the corkscrew or helix as it goes away from the antenna.
Mixed polarization is also known as elliptical polarization. It happens when linear and circular polarization mixes. Therefore, mixed polarization occurs when the tip of the electric field vector follows an elliptically designed corkscrew.
Moreover, it is easy for circularly polarized antennas to receive linearly polarized signals. The vice versa is also true. Additionally, the strength is equal in all cases. Whether the circularly polarized antenna is horizontal, vertical, or any other plane. This property is only applicable if it is direct to the incoming signal.
Applications for different types of antenna polarization
Various forms of polarization are suitable for broadcasting, radio communications, and wireless systems.
In general, the advantages and disadvantages of most forms of polarization are relatively the same. However, for some types of broadcasting, mobile communications systems, or wireless links for radio communications, these small differences may cause a significant effect.
For this reason, relevant antennas have related polarisations.
General radio communication
Linear polarization is the kind of diffusion currently used on most radio communications. The reason is due to radio antennas being more straightforward.
Mobile phones and short-range wireless communications
Over the years, the use of mobile phones and short-range wireless communications has seen remarkable growth. Moreover, a significant boost from cellular communications is evident. It is from cellular communications to Wi-Fi. It also includes other standards that improve short-range wireless communications.
Usually, these devices use linear polarization. Because linearly polarized antennas are easy to fabricate. Therefore, the base stations should have the same diffusion. Although some devices often use vertical polarization, several items, such as Wi-Fi routers, come with flexible antennas. These communications have signal routes that can reflect different surfaces. Therefore, the receiver’s diffusion is random, hence less of an issue.
Mobile two-way radio communications
Many outdated mobile two-way radio communication is still in use. Especially in emergency services and private portable radio uses such as transceivers in vehicles.
Moreover, these mobile two-way radio communications use vertical polarization. This is due to omnidirectional radiation in most vertically polarized radio antenna models. That implies that the antennas do not require orientation as the vehicle moves.
Long-distance HF ionospheric communications
Long-distance HF ionospheric communications use both horizontal and vertical polarization.
Horizontal polarization: In horizontal polarization, high-frequency communications use wire antennas. The antennas are erected with two poles. The wire antenna hangs between the poles. Therefore, the antenna is horizontally polarized.
In large multi-element antenna groupings, mechanical restrictions indicate the easiest way to mount them. It should be in a horizontal plane rather than in a vertical one. During construction, the high-frequency antenna components are at right angles with the vertical tower of the pole. Therefore, there is less electrical and physical interference between the two. Especially when using an antenna with horizontal components.
Vertical polarization: vertical polarization uses antennas with one single vertical element. Additionally, the vertically polarized antenna offers a low inclination of radiation. That will enable it to provide the correct long-distance reception and transmission.
Medium wave broadcasting
Medium wave broadcasting stations prefer vertical polarization. The ground wave propagation on the surface is better with this type of diffusion. Besides, horizontal propagation indicates a slight improvement for long-distance transmission in the ionosphere.
A standard mediumwave transmitter antenna works well on local coverage using ground wave propagation. Therefore, a vertically diffused antenna radiates equally in all directions. Moreover, a vertical antenna needs only the vertical component. Besides, a horizontally polarized antenna needs two poles.
In satellite radio communications, a circular polarization works best. Additionally, circular polarization has a lot of advantages. It is evident in propagation and overcoming the weakening of waves as the satellite changes orientation.
It is now clear that every type of polarization plays a significant role in a particular application. Therefore, selecting the correct form of diffusion is essential to enjoy its advantages. Finally, we offer the best cables to support your antenna system. Do not hesitate to contact us.