"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."{mos_sb_discuss:7}
JohnGalt:
Pacific Wireless has a "blade" sector that looks reasonable in terms of appearance, for under $200. 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"...
kukur (original submitter):
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. 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. 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*?
JohnGalt:
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.
kukur:
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?
JohnGalt:
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?
kukur:
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.
JohnGalt:
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.
kukur:
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... 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...
JohnGalt:
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...
JohnGalt:
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.
kukur:
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.
superdog1:
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.
GeeTek1:
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. Original thread location |
Installation Techniques 
