Inside Wireless: 3D Antenna Radiation Pattern

The 3D antenna radiation diagram is one of the most important antenna characteristics.

Main video takeaways:
- 2D plot (polar or other) gives a limited information about antenna radiation pattern
- 3D plot gives a complete information about antenna radiation pattern
- When a 2D plot is enough is a question of application. In WISP industry for example, a 3D one is necessary since all the antenna side lobes matter due to the noise being the no. 1 problem in unlicensed frequency bands.

Generally, the gain radiation pattern says what is the radiation intensity of the EM fields an antenna radiates in any direction. A 2D pattern gives this information in a selected two dimensional cut, most commonly in two planes perpendicular to each other - the 2 cuts give a limited information compared to the full 3D radiation pattern showing the gain in all three dimensions.

Isotropic antenna is a theoretical antenna that radiates with the same intensity in every direction. Its radiation pattern is therefore a sphere - drawing the radiation intensity in a given direction as vectors and connecting their tips, we get a surface which is the 3D radiation diagram.

The same can be done for any other antenna - the direction and strength of its radiation at any point in space can be expressed by a vector - with direction and amplitude. Connecting the tips of all the vectors forms a spatial image, we call 3D radiation diagram.

Since no real antenna is isotropic, let’s look at a parabolic dish - probably the most common antenna type. It focuses the EM wave energy in the direction of its main axis and it’s strongest there. Besides that it also has side lobes that are weaker than the main lobe, and are mostly unwanted especially in the unlicensed frequency bands where interference is the no. 1 problem.

Same thing here as with the isotropic antenna - we can plot the vectors from the origin on the whole spherical surface, but now, because the parabolic dish does not radiate equally everywhere, the vectors will have varying lengths depending on direction. Connecting the tips of the vectors, we get the 3D radiation pattern of this antenna.

3D vs 2D DIAGRAMS
The 3D diagram provides complete information about the gain of an antenna, since it shows the gain in every possible direction in 3D space - you cannot do better than that. This is why it is generally more useful than the 2D plot which is obtained from the 3D plot anyway - by selecting a specific slice from the 3D diagram.

The 3D diagram is more difficult to obtain than the 2D one, so historically the 2D plots became the standard in most engineering fields, but today, with powerful computers available to everyone and advanced antenna measurement setups capable of full 3D measurements, the difference is diminishing, but we’ll talk about that in another episode.

0:00 - Introduction
0:40 - 3D radiation pattern definition
1:10 - Isotropic antenna example
2:00 - Parabolic dish example
2:55 - When a 3D diagram is better?
3:29 - Historical perspective

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[helmutalexanderrubiowilson]

your videos are gold my friend... clearest antenna explanations in youtube

[inhdungho]

thank you very much, in 4 minutes, you have enlightented me more than my teacher

[mahmutsare]

Your explanations are quite useful to understand. Outstanding work, thank you very much!

[yohannesg.medhin]

Thank you for your pleasant explanation which helped us visualize the idea easily

[marlouragas]

What kind of antenna to be use in a gold locator

[mikec]

This is an awesome channel. Thanks for the refresh after all these years!

[shamssalehin]

Videos in playlist arent well arranged, its very difficult to learn step by step.

[ramza]

Do u mind if I ask? I have a few questions.
1. when the antenna radiated, does it means they go as far as the red region in their diagram or they go farther than that?
2. why the red region in the diagram has more power than other region when they are farther than the other? should farther more decrease power?

[big-boss-]

Awesome channel!! I have a question, why isotropic radiation doesn't exist?

[aishwaryagupta]

What is the interpretation of these terms in case of 2D radiation pattern
1)E_theta, phi=0
2)E_phi, phi=0
3)E_theta, phi=90
4)E_phi, phi=90

[minhquanam]

thank you so much! The best explanation

[geeell]

thanks for your videos, please make video(s) showing how QAM and OFDMA work together, especially in in 802.11ax (wi-fi 6)

[fm-angkor]

Very good channel! Thank you for sharing.
I have a question. Why are the side lopes of the antenna is cause the biggest problem of interference?

[RogelioecastellanosGonzalez]

Antenas of 2d es cuando las espirales 2 de be y cb se conjuntan para modular una suerte de impulsos que surjen de Exp z + 1

[bouabdellikhaoula]

give the expression filed electrique for reflector plane and dipole

[kishor_VUMZT]

very nice, , plz give radiation pattern of hexbeam, yagi, delta loop antena

[rkml]

Hi There, I am wondering if anyone has been able to provide a 3d Pattern testing facility for the public to use... I would like to know where there is one so we can send samples to have them test our equipment. If there is not, it would be cool to have a youtube channel showing how to test antennas and have a faceoff vs Brand and unbranded antennas.

[arhackteam]

i wish to use RF elements product put it not available her in Palestine and Israel