Size of “donut” signal waveform emitted from AX86U Pro antennas?

[SkippyP]

I have an AX86U Pro located on the main floor of my house. I have a basement and upper floor. I understand that the signal is broadcast perpendicular to the antennas (i.e. if antenna is vertical, signal radiates out horizontally) in a donut-like shape. Thus, I also understand that it’s generally recommended to keep the middle antenna positioned vertically and the two outer antennas at 45 degree angles (with all three antennas forming a W shape) in order to maximize coverage in a multi-floor home.

Having said that, does anyone know why I get better signal strength and better throughput all over the house with all three antennas oriented vertically instead of the W pattern? How large is the width of the “donut” signal waveform? Put another way, how “thick” would the donut be? If the “donut” was placed down flat on a surface, how thick would it be when measured vertically from bottom to top? I’d imagine it can’t be shallow since I’m getting full WiFi bars and strong signal on all devices on all three floors with all three antennas positioned vertically. The donut-shaped signal would need to be fairly thick to stretch and cover upper and basement floors, right?

 

[bbunge]

Because the Asus instructions for this router are to have the antenna vertical...
EDIT. There is also a fourth antenna inside the case.

 

[bennor]

Because the Asus instructions for this router are to have the antenna vertical...

The English user manual for the RT-AX86U Pro indicates, on page 9, the following antenna positioning:

 

[Tech9]

Put another way, how “thick” would the donut be?

Home routers have low gain antennas, this makes them almost omnidirectional, the radiation pattern is more like an apple:

In reality the antenna is just 5cm long dual-band dipole, not really optimized for any band. The rest is non-functional plastic used for marketing. Longer and thicker antennas create sense of more power on the consumer market. None of this is needed for good Wi-Fi.

 

[SkippyP]

Thanks @Tech9. That explains it.

In my environment, having all three antennas positioned vertically is so much better that in one corner of my house (one of the bedrooms on the upper floor), it’s a difference of 10db and ~200Mbps. In this particular bedroom (which sits above the garage and has been a particularly bad spot for signal), with antennas in a W pattern, I was getting between 250-300 Mbps with 2 out of 3 bars of signal. With antennas all positioned vertically, it’s full bars of signal (10db stronger as measured in the Apple Airport Utility app) and between 450-500 Mbps in that same bedroom.

 

[SkippyP]

Because the Asus instructions for this router are to have the antenna vertical...
EDIT. There is also a fourth antenna inside the case.

Interesting. The manual for this router says to position the antennas in a “W” pattern with the outer antennas at 45 degrees. Curious to know which instructions say to position them all vertically?

 

[Tech9]

it’s a difference of 10db

In theory there is no this much of a difference in antenna radiation pattern in any direction with simple dipole antenna. What you see is perhaps some beneficial in this specific case reflection. If it works better for you - keep it this way, nothing wrong with it.

Curious to know which instructions say to position them all vertically?

In theory for single level home the best antenna position is vertical, but this doesn't account for walls and objects reflections plus clients moving around - something you perhaps experience in your place. The goal is to get good signal where the clients are usually located. Wi-Fi is similar to turned on light in one room. You'll get brighter and darker spots on the hallway and other rooms around, behind the fridge or washing machine. Different material objects will reflect or attenuate the signal differently.

 

[Tech9]

The manual for this router says to position the antennas in a “W” pattern

The user manual and default settings are about covering what works okay in most cases. Not the best and not optimized for specific user environment. This is a consumer product and users are not expected to know details about how Wi-Fi works.

About radiation patterns - here is the one for the APs I have in use:

This means the horizontal orientation doesn't matter too much for this specific device.

Here is another radiation pattern for a different model AP:

This specific device may show different signal levels if turned slightly in right direction.

 

[bbunge]

While I do not mind being proved wrong, I do remember back in June 2023 when I got the AX86U Pro, as a replacement for a failed AX86U, that I checked the on line manual for the antenna position. The AX86U did recommend a \ | / or W antenna position but the AX86U Pro on line manual did recommend | | | or all vertical. Unfortunately, I can not prove the later as all the manuals for the AX86U Pro, which are newer than June 2023, show \ | / antenna position.
Regardless of the manual recommendation, as has been said in several prior antenna position posts by Merlin and other tech heads, the antenna position is dependent upon the environment. For me with a single floor house | | | works just fine. In fact the AX86U AiMesh node in my basement works well with | | |.
So, use whatever floats your boat. But remember, what works today may not work tomorrow!

 

[Tech9]

While I do not mind being proved wrong

There is no right and wrong in this case. Consumer manufacturers rarely post radiation patterns and it's all about trial and error process.