Difference Between Cross-Polarization and Co-Polarization: What do +45° and -45° mean?

Equipment Antennas
1

Hello experts,

Could someone please explain the difference between cross-polarization and co-polarization?

Also, what do +45° and -45° mean?

Cross-Polarization and Co-Polarization
Cross-Polarization and Co-Polarization996×443 32.8 KB

3

It relates to the orientation of the electromagnetic waves during transmission or reception by the antenna and is connected to the angle at which the electric field vector oscillates.

4

Thanks.

But why do we have two angles?

Wouldn’t one orientation be enough?

5

It provides a better chance for the terminal to capture the signal.

6

It’s used in MIMO to enable the transmission of multiple data streams over the same frequency, enhancing both capacity and signal quality.

7

Because it improves throughput, essentially doubling it without needing an additional frequency (NR-ARFCN).

It also enhances signal resilience to fading, as the two polarizations are less likely to encounter the same fading conditions or interference at the same time.

As a result, the signal’s reliability is significantly improved.

8

Thanks!

As far as I know, it refers to cross-polarization for massive MIMO antennas. The definition of cross-polarization is the ratio between the undesired polarization and the desired polarization.

My question is: why do we focus on the undesired polarization when our main concern is the desired polarization?

Why is cross-polarization used more frequently than co-polarization?

Does the -45° and +45° indicate that the polarization used for this antenna is cross-polar?

9

Cross-polarized antennas combine vertical and horizontal polarization components, enhancing signal reception and transmission in environments where signals may reflect, refract, or scatter.

This polarization diversity helps reduce signal fading and improves overall reliability, especially in challenging environments like urban areas with many obstacles.

10

Exactly!

11

Thanks, everyone.

Now, another question: What is recommended for use in 5G NR - cross-polarization or co-polarization?

Can we determine the appropriate type of polarization from the antenna datasheet?

12

I believe cross-polarization is more commonly used, and I think it’s because phones are more likely to be tilted rather than perfectly vertical or horizontal.

13

Cross should be used.