Antenna Polarization: Everything You Need to Know

This may surprise you, but antenna polarization is fundamental to battling poor signal reception.

And while it might sound complicated, it’s something you can determine from relative qualitative terms.

But what exactly is it, how does it influence a signal, and why is it necessary?

Read on to learn the answers to these questions and more.

What Is Antenna Polarization:

Antenna polarization is the orientation or inclination of the transmitted electromagnetic wave’s electric field vector with limited signal strength loss.

And that’s usually from the transmission tower to the antenna.

Typically, an electromagnetic wave comprises two main types of electric fields. And these fields are electric (Ef), e-field, and magnetic (Mf).

They run perpendicularly to each other, moving in a distinct direction.

Now the electric field wave axis moves either in a horizontal or vertical wave motion.

And it does this as it transmits the signal from the transmission tower to the antenna.

What Is the Formula for Antenna Polarization?

Interestingly, the formula for antenna polarization depends on the type of polarization in question.

Now this can be either linear, circular, or elliptical. You’ll notice a slight variation in the parameters for each polarization type.

For linear polarization, it’s

E = cos cos (2nf (t – z/c)) (x+y)

For circular polarization, it’s

E = cos cos [2nf(t – z/c)) x + sin sin (2nf(t – z/c)] y

And for elliptical polarization,

E = cos cos [2nf(t – z/c)] x =+ 0.3 sin sin (2nf (t – z/c)]y

Also, in all formulas, x, y, and z are the plane axis of the electromagnetic wave in all three panes of the electromagnetic (E) field.

Then the f represents the frequency of the wave.

In case you have two linear polarized antennas aimed at each other, to determine their polarization power loss, you’ll calculate the polarization loss factor as follows.

PLF = cos2∅^, where ^∅is the rotation angle between the two antennas. But if the angle is 90 degrees,, no signal will be transmitted.

How Does Antenna Polarization Affect Signal?

Correct polarization of the antenna increases the strength of the signal received.

For example, if you have two antennas close to each other aligned correctly with the same polarization, they will receive a stronger signal.

Now the same is true with incorrect polarization. So if the polarization orientation of the antenna is poor, you will receive an extremely poor signal from your antenna.

You may even receive no signal at all.

Therefore, the antenna’s polarization must be in line with the electromagnetic signal transmitted from the transmission tower.

Why Is Antenna Polarization Necessary?

See, antenna polarization is important because it helps you make the right decision regarding the choice of antenna for good signal reception.

Thus, you may consider purchasing an antenna that supports linear, circular, or elliptical polarization.

That said, it also depends on the type of signal transmitted from the broadcasting tower station, as this will provide you with the information you need for correct antenna placement for maximum signal reception.

More importantly, it helps deal with the reflection of the originally transmitted signal from the tower due to reception interferences from walls or other obstructions.

When there are such objects, they tend to change the polarization of the original signal. As a result, this affects your antenna signal reception.

Types of Polarization

Linear Polarization

As the name suggests, with this type of polarization, all the wave transmission lies in the same plane in a linear direction. It can either be horizontal or vertical.

For horizontal polarization, the signal transmission is in a horizontal plane.

On the other hand, in vertical polarization, the electrical field transmission occurs on the vertical axis.

For this reason, your antenna comes with vertical and horizontal fins. That way, it can receive the linear signal in horizontal and vertical angular inclination.

Remember that a change in the polarization state would make it hard for the linearly designed antenna to receive the signal.

Circular Polarization

Again, as the name suggests, circular polarization is a signal transmission in a circular form.

Unlike linear, circular polarization overcomes the effect of any reflection due to obstructions.

Now, circular transmission of the signal can occur in two ways.

Right-handed circular polarization: In this case, the electrical field rotates in the right-hand direction from the transmission tower to the antenna.

Left-handed circular polarization: For this one, the electrical field rotates in a direction opposite to the right-handed circular one.

Elliptical Polarization

Similar to circular polarization, elliptical polarization can be right or left-handed.

However, the signal wave fields perpendicular to each other are out of phase. That’s due to a difference in their magnitude.

As a result, the wave must move in an elliptical pattern in either a right or left orientation.

Also, you’ll easily notice an elliptical polarization in theory (in books) as it looks like a corkscrew.

Antenna Polarization Applications

Radio Transmissions

When it comes to transmitting radio signal waves, linear polarization is the most common type of polarization for transmitting such waves.

Mobile and Short-Range Communication Systems

Now more than ever, just about everyone uses a mobile phone.

Many of these devices use linear polarization to receive and transmit communication signals back and forth from the transmission tower.

More importantly, it’s easy to fabricate an antenna that’s receptive to linear signals in mobile phones. That way, the signal serves the needed purpose.

Medium Wave Broadcasting Media Platforms

Now these platforms use medium wave vertical polarization. And such transmissions work best for short-distance communication.

Therefore, the broadcast transmitter antenna works perfectly for such broadcasts.

(Caption: Broadcast transmission tower)

Benefits of Antenna Polarization

Below are the benefits of antenna polarization:

Reflectivity:

Granted, reflectivity due to interference is common with linear polarization.

However, circular polarization resolves the issue by transmitting the signal in all plane directions.

Absorption:

With circular polarization, it’s possible to maintain signal quality, regardless of any absorption during transmission.

Multipath:

See, multiple polarization presents a multipath effect common in linear polarization.

In this case, the two signals, one emanating from the transmission and the other formed due to obstruction, reach the receiver simultaneously.

When this occurs, it creates dead spots, thus compromising the signal quality.

But today, a dual-polarization antenna technology helps mitigate the issue, minimizing the short-delay multipath.

Inclement weather:

Raindrops can absorb the signal’s power when it rains, significantly compromising its strength and quality.

However, circular polarization can go around the signal degradation caused by the rain. As a result, the remains as it was originally transmitted.

Line-of-sight:

In cases where there’s obstruction due to buildings, walls and other objects, circular polarization works well. Thus, it maintains the communication link.

Diversity:

Because of polarization, there’s a diverse choice of signal.

It allows one to have antenna systems that generate signals in multiple polarization patterns.

As a result, it increases the options for better signal transmission.

Dual polarization:

See, you can incline two antennas in a way that helps you achieve a better reception of the transmitted signal.

In doing so, you reduce the loss due to polarization mismatch.

Note though, that the antennas must have the same polarization as the signal from the station.

(Caption: Dual polarization antenna technology)

Withstanding fading through slant configuration: Slant polarization helps mitigate the fading effect of a signal due to obstructive objects. Thus, it reduces possible interference by equalizing the signal levels from vertical and horizontal orientations.

FAQs

Which Polarization is Best for Antenna?

Of all the polarization types, circular works the best to eliminate many of the effects akin to transmissions. These include reflectivity, absorption, and multipath effects.

What Are Antenna Polarization Examples?

A great example of polarization in antennas is whip antennas found in cars. Another example is the antennas in the AM radio broadcasting towers.

Conclusion

Clearly, antenna polarization is an important aspect of successful signal transmission. And as we’ve seen, there are three primary types, linear, circular, or elliptical.

Also, there are several applications and benefits of a polarized antenna.

So now you have all you need to know about polarization to make the perfect choice of antenna.