superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
 ·WaveCrazy.Net
| CPE's with less than a 12dBi antenna?
As time goes on, I find myself having to install more and more customers that are very close to the PoP. Even with a small all in one CPE with a 12dBi antenna, it is still over kill.
Logic tells me to install a CPE with a lower gain antenna, but that presents problems too.
With all of the SOHO wireless routers being installed every day, using a low gain antenna seems to just aggravate the situation, as it's wide beam picks up EVERYTHING, so I am thinking that I need to install more of these customers with a higher gain antenna and a LOT less power.
While it may seem strange to use a 19dBi grid on a customer that is only 1 mile away, the resulting narrow beam aimed into the sky picks up a lot less garbage.
This brings me to my next question, methods of bringing down the power levels entering the antenna without 400 connectors and 20ft of LMR400 or RG58. This method gets expensive after awhile and looks really stupid on an install.
I was wondering what everyone thought of this debate/dilemma, and if anyone has a source for inexpensive/cheap RF chokes that could be used on every install with a higher gain antenna?.
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John Galt
Spricket24
Premium
join:2004-09-30
Oceanside, OR
| Here's what you need:
»www.minicircuits.com/pages/dat_a···tor.html
Finding it in an appropriate package will be the challange. These are also available but not cheap by any means:
»www.pasternack.com/subCategory-A···-20.html
I saw another post on another site that suggested using RG-174 to attenuate. Perhaps it would be possible to replace the panel coax with a coil of the correct length to knock the signal down but have it small enough to insert into the CPE.
Just a thought....
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A is A |
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MWI
join:2006-03-09
Mooreland, IN | reply to superdog
This is what I have done before, sort of same situation, I just changed the polarity of the antenna at the cpe. it will normally drop about 15 to 20 db. worked good for me but you may have other reasons not to. Hope this may help. |
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electric6
@sbcglobal.net
| reply to superdog
said by superdog  :I was wondering what everyone thought of this debate/dilemma, and if anyone has a source for inexpensive/cheap RF chokes that could be used on every install with a higher gain antenna?. Fixed coaxial attenuators with SMA connectors and dc to 12 GHz bandwidth are not very expensive. |
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John Galt
Spricket24
Premium
join:2004-09-30
Oceanside, OR | said by electric6 :
Fixed coaxial attenuators with SMA connectors and dc to 12 GHz bandwidth are not very expensive.
Link?
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A is A |
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Equis
Premium
join:2005-03-18
Australia | reply to superdog
I test all my radios before they go out.
Some are down 10 - 15 db, Instead of replacing under warrenty I just use them for the close in shots  |
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electric6
@sbcglobal.net
 from:
John Galt
| reply to John Galt
said by John Galt :said by electric6 :
Fixed coaxial attenuators with SMA connectors and dc to 12 GHz bandwidth are not very expensive.
Link? these or similar
»cgi.ebay.com/5pcs-Suhner-3dB-SMA···ViewItem |
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lutful
Premium
join:2005-06-16
Ottawa, ON
 ·TekSavvy Solutions..
edit:
January 10th, @07:47PM
| reply to superdog
For 2.4Ghz CPE, you will pay much less for 2W rated 0-3Ghz SMA model than a 50W rated 0-18Ghz N-model. Back in my Radialink days, I sorta influenced a Chinese manufacturer to design a very compact 500mW max RF attenuator for similar purpose.
EDIT: The Mini-Circuits $11.95 DC-6Ghz VAT-X+ models (mentioned by Dzero later in this thread) are perfect for both 2.4Ghz and 5Ghz.
BTW some Atheros radios in PHY test mode can output 0dBm to max dBm in 1dB steps. IMHO that is a much better approach so ask your vendor to support that in firmware. |
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LLigetfa
join:2006-05-15
Fort Frances, ON
| reply to lutful
Re: CPE's with less than a 12dBi antenna?
said by lutful :BTW some Atheros radios in PHY test mode can output 0dBm to max dBm in 1dB steps. IMHO that is a much better approach... How does that help the too hot (and too sensitive) on RX issue?
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Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
·WaveCrazy.Net
| reply to MWI
said by MWI :This is what I have done before, sort of same situation, I just changed the polarity of the antenna at the cpe. it will normally drop about 15 to 20 db. I have also done this. Generally speaking though, lower dBi antennas have wide beam patterns in both directions, so while it cuts the intended signal down, it still has to deal with the garbage it sees
said by MWI :worked good for me but you may have other reasons not to. Hope this may help. I guess my other reasons are trying to get a smaller beam/pattern on the CPE antenna in hopes of cutting down on interference.
It is also possible to try and use a side lobe by pointing the CPE up into the sky. I have done this on a few locations also, but here again, even pointed upwards, the lower gain panels have quite a large area they will still cover, hence my thoughts about choking the RF and using a higher gain antenna.
I also just realized that some of the all in one 19dBi units allow you to turn down the juice to 16mW (8186 units). I may try this in the future?.
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AMD Phreak
Please do the needfull
Premium
join:2003-12-14
| reply to superdog
Just tossing this out here....
Don't forget that when you insert loss you are loosing power on both TX and RX. If the goal here is to knock down TX from the CPE, it will certainly do that but at the same time you will be loosing gain on the RX side.
I know everyone knew this but I thought I'd toss it out.
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"No job is so important, and no service is so urgent that we cannot take the time to do it safely."
-- AT&T
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it." |
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EMC_guy
join:2007-10-13
Sharbot Lake, ON
 ·Rogers Hi-Speed
| said by AMD Phreak :you will be loosing gain on the RX side. Agree with you completely. It makes no sense to lose 10-20dB on RX path trying to lower TX power!
AMD Freak, by the way LNA chips (on RX) handle -100dBm input signal levels while PA chips (on TX) handle +20dBm levels. There is no way to make one chip do both, so TX and RX gain paths are usually independent. Even bi-dir amplifiers auto-switch between PA and LNA.
Many Atheros radios come with certification test mode that allows us to lower TX power from the transceiver (usually down to -10dBm) and some radios also provide a few dB gain adjustment on the external power amplifier IC. Although FCC/IC does not care much about the RX, some test software provide access to LNA gain and RX sensitivity adjustment. I wonder why WISP firmware developers could not hook into those. |
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Dzero
Premium
join:2005-07-23
Illinois
| reply to John Galt
Minicircuits has inexpensive SMA attenuators.
$11.95, DC to 6000MHz (VAT-X)
I just bought 6 of them a month ago. They also have kits with a variety of values at a discounted price.
»www.minicircuits.com/products/at···xed.html |
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John Galt
Spricket24
Premium
join:2004-09-30
Oceanside, OR
| said by Dzero :I just bought 6 of them a month ago. html Good find!
They also have these:
»www.minicircuits.com/products/ad···ors.html
if you need or want to change connector styles at the same time.
Keep it nice and neat.
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A is A |
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lutful
Premium
join:2005-06-16
Ottawa, ON
·TekSavvy Solutions..
| BTW back in 2006, most of these adaptenuators were SMA/BNC and covered DC-2Ghz only. I will check if they have come out with higher frequency SMA/N connector versions.
I agree mini-circuits is a good USA source for a wide variety of packaged RF assemblies - I used many and have occasionally mentioned them. I see they are easier to order now and prices have dropped a lot too.
»Re: test set up question for Canopy
»Re: Anyone recommend a good RF splitter? |
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Dzero
Premium
join:2005-07-23
Illinois
| reply to John Galt
John, Yes those could come in handy. I noticed them when I was ordering and was hoping they had some in RP at that price. It could have saved me a pigtail.
And to add to Lutful’s comment, it was my first time ordering from Minicircuits and I’ll say it was an overall good experience, very helpful people there. |
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cmaenginsb
Premium,MVM
join:2001-03-19
Palmdale, CA
| reply to superdog
I think the idea EMC guy is that if you purchase a narrow beamwidth antenna you end up with a higher gain and higher rx and tx values in the range of overloading the receivers on both ends of the link.
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CCNA, Comtrain Certified Tower Climber |
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