I own two mikrotik routers 411u + 433au with two r52 wireless cards (17db)
I use two panel antennas with the following specs:
product code INT-PAN-23/5X-HV
frequency 5150-5850MHz
impedance 50Ω
VSWR (max) 1.3
gain 23dBi
beamwidth (-3dB): horizontal 10°
beamwidth (-3dB): vertical 10°
front to back ratio > 35dBi
cross polarization > 24dBi
I bought them to link two location with distance 6km and 500m height differnce.
I got :
signal stregth -92
noise floor : -105
snr : 13
The tx power was 17db the maximum of the wireless card, I lowered the power to 15-12-9-3 db and the results was the same. -92 , -105 , 13 . ±1.
The two antennas failed to connect. What should I do?
If a replace the R52(17db) with R52hn (25db) in both routers would be any difference?
The frequency is 5180 mhz .
How much is the maximum distance for these antennas and wireless cards?
on 6km link using R52 cards and 23dBi antenas ?
i would expect -63dB signal level
So if you have so low signal, ill ask why ? Are the antenas usable for this 5180MHz band ?
Did you tryed another cards (another R52) or another type of antenas?
If everything is OK the calculations are very accurate, not more that 3dB difference betweet calculated and real values
Do you have LOS between the points?
Do you have the fresnel zone clear enough?
Is the Antenna Polarization the same for both sites?
Are all the cables correctly plugged in?
You have serious problems if your signals are so high..
http://en.wikipedia.org/wiki/Fresnel_zone
I cannot find the link calculator with Fresnel Zone calculation too, i usually use RadioMobile, but might be a PITA to configure.
If you plan to make a lot of links, RadioMobile tool is a must.
your pics show 2 problems, fresnel related:
1 the trees @ point B are too high, you need to raise your pole at least of 3-4 meters
2 the mountain on the right side of the antenna A (from point b view) might be a problem aswell, (not sure because the point is very far away)
See one more photo, i think that the trees should not the problem. I thought that maybe the antennas @ (1.8ghz) or the power cables might cause some problems.
the second photo with “Antenna A” show trees some hundred or so meters away. You’re LOS is just overshooting these thus the trees are almost definitely in the Fresnel. The moisture (water/vapour) in the leafs consume the electromagnetic energy of the radio waves. And the surface of the leaves also reflects the energy. Trees are killers when it comes to wifi radio links…
I see another problem: transformers in the elec. poles. They can radiate high magnetic or fields or radio waves. That COULD affect your radio’s too…
Is this high telcon tower really this close or is it illusion/artist impression?
Why not use this tower? Much higher and more away fm. the power transformers.
Currently one of the routers has been send to rma so I can’t make any tests. I didn’t know that the leaves could cause problems.
My antenna was 2 meters higher but I have cuted the flagpole for installing it easier because I was using a ladder and I was afraid the wind if I was that high.
The trees and bushes in the other picture are about 120meters far away.
The tel. tower is not mine to use it.
No. See my previous post.
Cut the trees at distant of higher your masts.
You can try to use even higher gain antenna’s and more powerfull radio’s but you get more signal disortion at the recieving end as bonus. So high levels but low quality.
You are having a typical fresnel zone problem. we have 3 fresnel zones. These are 1st, 2nd and 3rd. if any obstruction encroaches into the 1st zone, you will be having signal with low SNR but the link will be working though this will have negative effect on the throughput of the link. however if the obstruction encroaches into the second fresnel zone, the SNR will be very low (as in your case) and the link will not be able to carry data AT ALL. Finally, if obstruction encroaches into the 3rd fresnel zone, then the link will not be established.
The first approach to solve your problem is to clarify that the board and cards are working very well by testing inside your lab or on the ground. at this point take note of the values and proceed to the site.
At the site, take note of the tilt angle (as i noticed that point A is higher than point B above sea level) if tilt angle cannot solve the problem, then consider increasing your height especially at the site you have lots of trees.
you can consider 900MHZ is it is unlicensed in your country.
Because I can’t cut the trees and secondly to raise the antenna 2-3 meters higher is a little bit difficult If I replace the cheapest part in the wireless link which is the wifi card from R52 to R52 High power is it going to be better?
I have just received the router from the rma and I realized tha also the wifi card of the specific router has problem. So because I am going to buy a new one, will be better a R52 Hn instead of a R52?
If this would be my link and I would have ample budget than I would try the following, in that order:
Check that all connectors are properly fit and clean and well protected against moisture.
Make sure antenna and radio and board have good one common earth connection.
Scan on both end for which frequencies are free. Than pick one free one as high as possible but also keep as much distant to other channels as possible. Scan on 5, 10 and if possible on 40Mhz as well to see if the spectrum is not used in these ranges. Better would also to have a spectrum scanner look at it but these are very expensive.
Raise the height of the antenna. Even if you can gain only 1 mtr. every meter is one… Just an extra pole on top of the other, eventually with some support wires to keep it sturdy in the wind, can’t be such a big issue and is cheap.
bears medium (to high depending your budget) costs
bears little to medium costs.
Actually putting higher powered card gives you the least change of improving results in regard to have a good quality connection. Although the higher power at the other end (you have to do it on both ends) gives more signal, it also gives more multipath receipts from same radio.
One thing I also would try is to setup a 802.11n link. This will handle the tree distortion much better in my opinion. But this is something not really proven to be true on this forum so some uncertainty in that respect is there.. But you could give it a try although you need other radio cards and if you want to use both chains you also need dual polarity antenna. Now here your costs go up! (http://www.interprojekt.com.pl/jirous-jirousjrc29duplex-5ghz-dual-29dbi-dish-antennas-p-1092.html)
Good luck!
P.S.
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