Yes. The line-of-site is no question and there are no obsticles in the fresnel zone. The main site has a 100ft LMR400 cable (low loss), two of the non-root sites have under 75ft and the 1.9 mile site has a 200ft cable. The calculations for the long cable with the low loss show that I should be well within the range for connectivity.

To determine the theoretical distance you can operate this setup, we require the following information (for both ends of the link):

-- Bridge types,

-- Datarate,

-- Antenna type, Antenna gain,

-- Cable loss/100ft, Cable length

When I make the following assumptions:

2xBR340s,11mbps,12dBi Omni to 21dBi Parabolic, 100ft at 6.7 to 200ft at 6.7

I get the following (theoretical) results:

max distance w/10dB margin = 1.54 Miles

Required Antenna Height above obsticles (in feet) = 22ft

Fresnel Zone = 17ft

When I change the datarate to 5.5Mbps, I get a max distance of 2.45miles, so that might be a simple test that may stabalize the link.

Ultimatly, you may need to try and eliminate some of that 200ft by bringing the bridge closer to the antenna. The BR350 is good for this as it has inline power support (you can't have a mixed br340/br350 link though - you need the same bridge type at each end of the link)

Your assumptions are all correct except for the cabling. The lengths are o.k. but they are using low loss 3dBi/100ft for the entire run except for a 2ft piece of the standard Cisco cable between the low loss and the bridge device. It looks something like this (if you can visualize it). The [] is the bridge and the (- is the dish. How much loss per connector? []----===========----(- . One of the non-root sites has the standard Cisco cable and the signal is just O.K. but acceptable. I swapped the cable at the main site with the Standard Cisco cable just to rule out the Low Loss cable and the signal was actually worse, so it is making an improvement. Thanks for your help!

well.... Im a bit out of my league here, but Ill put my money on those 2ft interconnects being the problem. can you terminate the low-loss cable directly on the bridge/antenna?

How about my suggestion of lowering the data rate (1,2,5.5Mbps) to see if that make the link stable at least?

I have suspected the 2ft interconnects myself, but the cable guy checked them out o.k. and when I by-passed that cable with a one piece Cisco cable the signal was actually worse, so it disproved my theory. Lowering the data rate does increase the signals, but I suppose the the issue is that this should work fine at 11 Mbps for this short distance.

hmmm, I'm just guessing here, but here is what we think we know:

200ft of low loss cable (3dBi) should work

200ft of cisco cable (6.7dBi?) will not work

Here is what we dont know:

2ft of high loss cable connected (loss) to 200ft of low loss cable conneccted (loss) to 2ft of high loss cable.

If those 2ft cables are the cisco interconnect cables, they have a high loss and are for connecting a cisco bridge to an antenna over a very short distance where the effect of the high loss is minimized. I don't know what additional loss the connections between the cables introduce, but it could well be significant.

Not sure where you got your numbers.

100 foot of RG-8/9913 has a loss of 8 to 9 dB. (Almost 90% of signal strentgh)

100 foot of RG-58 is more like 19dB (99% loss).

So 200' of anything without an amp is a problem.

I got the numbs from the cable guy. Obviously I lack where the cable starts out to the ant. I have a pic of the cable markings and can e-mail it to you if you send me your email [ frank.capra@us.logical.com ]. The markings on it say "84147 Andrew LDF5-50A Heliax Coaxial".

I don't know if you seen my post about the amp.,,,,Can I legally use one?

excuse my ignorance, but this has not come up before. How do you check the polarity of the antennas? Cisco says the ants are vertically polarized. How would you go about verifying polarization? I really appreciate your help and new ideas. Thanks

If two vertically polarized antennas are pointed at each other, but one is rotated 90 (or even 20) degrees they won't see each other. (This is sometimes done on purpose.)

Just make sure they are all oriented the same. If they are all the same type, it's as easy as checking that the pigtails or connectors all stick out the bottom/top or left/right.

If they are not all the same, check the docs so you know which way is 'up' on each.

There are multiple interpretations of the FCCs proclamations.

If you use an amplifier, at the very least test the final output power (rather than relying on just the dBm math to tell you).

CISCO cannot sell amplifiers because they would be responsible for such testing, so it's easier for them to say it can't be done.

BTW - Have you considered moving the bridge closer to the Antenna?