Antenna Setup

[1929]

Which the best setup of antenna for use with the SR71? Omini antenna or sector?
I will want to put 3 SR71 in the base. Will be it able to have interferences between them, if I use omini antenna?

[sarpkaya]

Where did you found SR71? Which store?

[1929]

Where did you found SR71? Which store?


I found it in Paraguay. $ 102,00 www.flytec.com.py
I'm a Brazilian. The Paraguay is very near for me.

[1929]

I am in the doubt about which the best antenna setup for MIMO.

Omini or Sector in use outdoor?

[adaniel_baigorriaum]

Hello, I suggest you use panels as a panel of 8dbi to tx and one of 12dbi or 16dbi for rx, with a separation between sectors of 1 meter. But if you can get in some way you measure in ROE for the antenna with the Pigtail better. 8)

[1929]

My doubt is because the I MIMO works with reflection of waves.
Would be able to the sector antennae lose this benefit of the 808.11N protocol?
However, the sector antennae be able to have a reach outdoor improved.

[UBNT-Mike.Ford]

Hello 1929,

This indeed does work outdoors but there are slight tricks to it. We will release all this information along with our test results soon.

Thanks,

Mike

[1929]

Hi, Mike!

I am awaiting your tests with the SR71A and the best setup of antennae.

If I use 3 omini antennae, which the horizontal distance that should put between them? I imagine that should have an ideal distance for a perfect marriage of impedância between the 3 antennae omini. It would be multiple of half-wave? Or this characteristic is not very important?

[WHT]

If I use 3 omini antennae, which the horizontal distance that should put between them? I imagine that should have an ideal distance for a perfect marriage of impedância between the 3 antennae omini. It would be multiple of half-wave? Or this characteristic is not very important?
I can't find the links to the posts, but here's what I said:

PostPosted: Mon Dec 29, 2008 8:46 pm

"Received a couple of SR71-A cards......What type of antenna array should be used? I was thinking three 90degree four foot Til-Teks all vertical. Should I use a horizontal sector for one of them instead of all three vertical? How should they be spaced? 3ft, 6ft between each sector?"

"A couple of cards" leads me to believe you'll have the LiteStation mounted up in the tower with several SR71 inside with each SR71 connected to its own single one antenna (defeating the MIMO feature) to achieve omni-directional deployment.

"all three vertical" leads me to believe you'll have the LiteStation mounted up in the tower with ONE SR71 inside connected to three different-direction-pointed antennas to achieve omni-directional deployment.

I'm going to assume this is a centrally located AP tower for a WISP deployment.

Going on that assumption, many MIMO projects will fail to meet expectations as there is insufficient MIMO antenna separation. I'll toss out the observation that one foot antenna separation per one hundred range is a good starting point

Therefore a correct implementation would require twelve antennas total.
* Vertical spacing of the three antenna array for one card should be on the order of 100 feet to avail of the MIMO antenna diversity
* Each of three antennas in the three-antenna array should point in the same direction.
* Each array of three antennas should have at least ten feet of horizontal spacing between the arrays.

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PostPosted: Fri Jan 09, 2009 7:11 am

Type "N" is advertised as faster speed and longer ranges. But they don't tell you those are mutually exclusive...choose one or the other, but not both. Nor do they tell you its effective up to a few tens of feet.

Since MIMO technology avails itself on alternative signal paths. One path might be poor and another better, so it grabs the data from the best path.

While you may have seen references to using it, have you seen field tested before and after comparisons? I'll bet you see something like, "We tested a high priced XZY brand of antenna that promises amazing performance and it works great!"...never mind the fact a more traditional (and lower cost antenna would have preformed the same).

For MIMO to work, there has to be a significant difference in the signal path. This is similar to antenna spacing diversity. If you are shooting twenty miles, towards two antennas spaced only a few feet apart - both antennas are pretty much seeing the same path. But if you space them thirty feet apart, then one will see a different path then the other.