MA-ANT-25

[PSKlauton]

Hi All,

We've been toying around with mounting options for hanging MR86 with 2x ANT-25 antenna's. This will be hanging from a ceiling in a warehouse. We are using a custom made mounting bracket with the AP on the back and the Antennas on the front. I was wondering whats the minimum separation (if any) between the ANT-25s? Please see pictures for reference.MR 86 on back

Any guidance on this would be appreciated?

Kind Regards,

Kyle

[Madhan_kumar_G]

Hi,

How to determine proper antenna spacing

As a general rule Southwest Antennas recommends customers place omni-directional antennas a minimum of one wavelength apart from one another, while three wavelengths apart or greater is preferred. 

Simple Wavelength Calculation

You can use the following simple equation to calculate the wavelength size at your operating frequency of choice:

Wavelength Online Calculator

https://www.southwestantennas.com/calculator/antenna-wavelength

Additional Considerations for Directional Antennas

For directional sector antennas, spacing the antennas at least a single wavelength or more apart (three or more is preferred) is also recommended by Southwest Antennas. However, due to the wide angle of the horizontal (azimuth) beamwidth and narrow angle of the elevation beamwidth of these antennas in comparison to their omni-directional counterparts, a few additional suggestions are warranted:

1. Due to the narrow elevation beamwidth, these antennas can be stacked vertically to avoid coupling issues entirely.
2. Sector antennas tend to be larger than omni-directional antennas. Due to the extra size of the radome, the antenna elements within the radome may be spaced appropriately to provide great than one wavelength of separation, even if the antennas are installed directly next to each other. The manufacturer of the antennas should be able to give you more information on the general location of elements within the antenna, and if additional spacing is necessary to prevent coupling.
3. If the antennas are not required to be pointing the same direction, they can be rotated to minimize the signals propagating from each antenna from interfering with the other antennas in the array.

Reference: https://www.southwestantennas.com/articles/application-example/antenna-spacing-considerations-multi-...

[PSKlauton]

Hey,

Thanks for the information. 

So to be clear, based on those results, I just have to make sure the antennas are 36cm's apart on the bracket? Based on 2.4GHZ. Am I correct to assume that this will okay for the 5GHZ as well?

Kind Regards,

Kyle

[Madhan_kumar_G · Accepted solution]

Hi,

When three times Wavelength apart is considered,

for 2.4 GHZ, Max Frequency = 2.5 GHz

Wavelength = 12 cm

3 times wavelength = 36 cm or greater apart is preferred

for 5 GHZ, Max Frequency = 5.875 GHz

Wavelength = 5.1 cm

3 times wavelength = 15.3 cm or greater apart is preferred

And So, it should be alright to place both at 36cm apart.

[PSKlauton]

Sorry, one more question.

Would the 36cm be a gap between the two antenna's or would the gap be between from the middle of antenna A to antenna B?

[PhilipDAth]

Even 2.5 wavelengths apart is pretty good.

[dbq]

I like your design, I might steal it. Does it matter if the ant-25s are mounted vertically (cables running down, cisco logo at bottom right way up) or horizontally (cables running at side with cisco logo to right on a 90 degree angle)?