kukur
join:2003-10-29
Saint Maries, ID
| Good looking antenna...
Over the weekend I installed a Hpol antenna (16dbi 120*) and Tranzeo AP (200mw) I had ordered, but have run into one of those little-big problems.
The AP is going up at my home. My plan was to mount a mast (15') off the back shed (12' tall) and get the antenna up around 25' to clear my roof line.
Now that it is up, it looks like the beam is shooting right into the peak of the roof. Maybe half is getting over and half is being reflected somewhere into oblivion by my metal roof. I still get a signal 2 miles out, but am concerned with snow accumilation in the winter on the roof will block out the signal.
Going higher isn't possible in this location due to overhead powerlines.
I am thinking of revising the plan of attack and trying to mount an omni off the front peak of the house to eliminate the roof all together. I know omnis aren't as efficient, but wouldn't be able to mount a normal sector off the side of the house. Omni is smaller, lighter (easier mount) and will keep the neighbors and wife happier.
Two questions...
I am trying to get the signal 2 miles from the AP. Is this within a normal range of an omni? (So far we have only used omnis donwtown with a couple block range needed.)
If the omni is mounted to the peak, come winter will I get too much interference from the backside reflection if say 2 feet of snow collects on the roof? (It is a steep pitch, so not much more than 2ft accumulates).
OR... does anyone know of a less obtrusive looking/size 120* sector antenna that could be used in this application.
TIA |
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John Galt
What...me panic??
Premium
join:2004-09-30
Happy Camp
| Pacific Wireless has a "blade" sector that looks reasonable in terms of appearance, for under $200:
»www.pacwireless.com/products/sector.shtml
Omni's are fine, as long as you need to radiate in every direction, and if you can stand the noise. I did notice that you have installed a HPOL...do you need to be in that polarization in particular? In my cursory search I could not find an omni HPOL...
A short mast will solve the snow problem. You need to mount it on something anyway. Keep in mind that anything that is up in the air will look smaller than on the ground...so don't let the Wife, or the neighbors, see it "on the ground"...
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A is A |
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kukur
join:2003-10-29
Saint Maries, ID
| John,
Thanks for the reply... I was just on pacwireless site and found they do have a Hpol omni... looks like the blade sector as well.
»pacwireless.com/products/omni.shtml
Do I need Hpol? Dunno. This was/is my first implementation of the Hpol. We have trees, in some places lots of them.
It seemed that even with the roof-in-the-way problem I was getting a good signal. Perhaps this isn't the case with Hpol vs. Vpol, but I found that I either had a good signal, or I didn't... unlike with the current Vpol APs we have now which can get iffy.
I will take a look at that sector.
Thanks again. |
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kukur
join:2003-10-29
Saint Maries, ID
| reply to John Galt
Would we be better off trying a 180* "sector?"
All they really are is an omni with a shield most of the time correct?
Is there much difference in performance between an omni and a 180*?
»pacwireless.com/products/images/···0-12.jpg |
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John Galt
What...me panic??
Premium
join:2004-09-30
Happy Camp | A 180 degree sector will have 3 dB more gain than an omni, typically. If you don't need to feed in the other direction, you might as well use the sector.
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A is A |
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kukur
join:2003-10-29
Saint Maries, ID | John,
At 2 miles +-, with the location of the AP on a slight hill, would you recommend going with a lower 9 dbi - and get a wider beam, or do you think I would need the extra gain to reach that far?
Thanks again |
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John Galt
What...me panic??
Premium
join:2004-09-30
Happy Camp | It depends what your objective is...are you needing to provide signal to a number of subs in the served area, or just a PtP link to another site?
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A is A |
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kukur
join:2003-10-29
Saint Maries, ID
| This is a multipoint AP location - Probably not more than 20 users.
We are trying to get into a dogleg area our current towers can't reach into.
There is a small (40 house) development we are trying to reach that begins at 1.4 miles and ends right aroung 2 miles.
One other customer (business) is located about 90* +- from that housing development that wants internet as well. This customer is slightly elevated compared to the development, but not higher than the AP will be. |
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John Galt
What...me panic??
Premium
join:2004-09-30
Happy Camp
| You need to do a link calculation...that will tell you if the 9 dB is sufficient to service the far end of the development.
»my.athenet.net/~multiplx/cgi-bin···main.cgi
Use the furthest distance in the calc...this appears to be a bit daunting, but work through it....it is not that bad.
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A is A |
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kukur
join:2003-10-29
Saint Maries, ID
2 edits | John,
Forgive my ineptness... I plugged all the numbers into the link you gave me and got a spew of numbers out, but couldn't find anything that said.. "you can go X distance."
So I found this site...
»www.signull.com/fsc.php
And put in these numbers...
Tx Pwr 15dbm (200mw)
Rx sensitivty 89 dbm (per Tranzeo)
TX Gain 9dbi
Rx Gain 15dbi (per Tranzeo)
Tx Cable Loss - 1 db (15ft)
Rx Cable Loss - 0 db (integrated)
Signal Margin - 15db (not sure what this should be)
I was given the response...
Total Gain 120 - Max Distance 6.16 miles
Does this look/sound right?
What is a good Signal Margin suppose to be?
Thanks for taking the time on this...
Lawrence |
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John Galt
What...me panic??
Premium
join:2004-09-30
Happy Camp
| said by kukur  :Thanks for taking the time on this... Glad I could help...
It looks OK to me. The Signal Margin is related to fade...from heavy rain, for example. More is better, 20 dB is great, 10 dB is marginal, so it looks like you are right in between. Remember, that is for the maximum distance of the link...if the link is shorter, the margin improves the closer you get.
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A is A |
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kukur
join:2003-10-29
Saint Maries, ID | Great!
I ran the numbers after reading up on Signal Margin. with 22 dbm margin I can hit 2.75 miles.
So it looks like I am going to give the Hpol omni a try and see how it works for us.
Appreciate all the info. |
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John Galt
What...me panic??
Premium
join:2004-09-30
Happy Camp | |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
| reply to John Galt
said by John Galt : In my cursory search I could not find an omni HPOL... See our friends at Winncomm. I have one in service from them and it is the best thing next to sliced bread. It is Russian made(As are a lot of Winncomm antennas) and it weighs about 7 pounds. I am sure it is a slotted waveguide with a heavy duty mount and cover. It appears that this thing could take a few bullets and still work. The downside is cost, as I have $450 in it, but it sure is a great way to set a small PoP up in a high noise environment.:)
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GeeTek1
join:2005-03-20
Del Rio, TX
| reply to kukur
If your objective is to service 20 or so customers at around 2 miles away, you might consider putting in a PtP link to the center of the customer base, and feed an AP hooked to an omni at the distant end. It would reduce the customer hardware needed to get them connected. You could then use 24Db grids for your PtP link. With 200mw radios, you would have a gawdaful strong link with little expense. |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
| said by GeeTek1 : With 200mw radios, you would have a gawdaful strong link with little expense. Agreed, and You may also be a gawdaful amount over FCC power limits.:D
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GeeTek1
join:2005-03-20
Del Rio, TX | Actually it's a pretty sweet limit for point to point only. FCC limit using the 24Db grid is 250 mils. The radio in question is only 200. |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
| said by GeeTek1 :Actually it's a pretty sweet limit for point to point only. FCC limit using the 24Db grid is 250 mils. The radio in question is only 200. Well, When I ran the calcs., this is what I got:
Highest transmitted frequency : 2483.000 MHz (2.483 GHz)
Wavelength : 4.753 inches (12.074 centimeters)
Transmitter RF power output : 23.010 dBm (199.989 milliwatts)
Transmit cable type : Times Microwave LMR-400
Transmit cable length : 50.000 feet (15.240 meters)
Total transmit cable loss : 3.370 dB (0.067 dB/foot 0.221 dB/meter)
Total transmit connector loss : 0.500 dB through 2 connectors
Total transmit cable loss : 3.870 dB
Transmit miscellaneous losses : 1.000 dB
Transmit antenna peak gain : 24 dBi
RF input power to the antenna : 19.140 dBm (82.035 milliwatts)
Allowed input power to antenna : 24.000 dBm (251.189 milliwatts) Per FCC Part 15 rules
Transmit antenna height : 60.000 feet (18.288 meters)
Distance to the radio horizon : 10.629 miles (17.106 kilometers)
Receive cable type : Times Microwave LMR-400
Receive cable length : 40.000 feet (12.192 meters)
Total receive cable loss : 2.696 dB (0.067 dB/foot 0.221 dB/meter)
Total receive connector loss : 0.500 dB through 2 connectors
Total receive cable loss : 3.196 dB
Receive miscellaneous losses : 1.000 dB
Receive antenna peak gain : 24 dBi
Receive antenna height : 25.000 feet (7.620 meters)
Distance to the radio horizon : 6.861 miles (11.042 kilometers)
Received power level : -47.558 dBm (936.626 µV)
Receiver's threshold : -82.000 dBm (17.762 µV)
Thermal fade margin : 34.442 dB Nothing could take this link out.
Probability of outage : 0.01 %
Total free space path loss : 110.503 dBi over a path length of 2.000 miles (3.219 kilometers)
Peak transmitted EIRP : 42.140 dBm (16369.804 mW) This power output violates current FCC rules for point to multipoint links.
Midpoint 0.6 Fresnel zone boundary : 25.043 feet (7.633 meters)
Maximum space wave communications distance : 17.490 miles (28.148 kilometers)
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jdmarti1
Jack
join:2004-06-15
Oilton, OK
| Tim,
I think you and Geektek are talking about the same thing.
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You could then use 24Db grids for your PtP link. With 200mw radios, you would have a gawdaful strong link with little expense.
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kukur
join:2003-10-29
Saint Maries, ID | reply to GeeTek1
GeeTek,
We did think about that... and it may be our backup plan. However there is one business customer we want to inlcude that isn't near the homes and can't see the housing development. |
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