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Min Distance from VHF Antenna |
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Written by keefe007
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Wednesday, 15 November 2006 |
" What's the minimum separation I should have between a 2.4 cluster and a 150 Mhz VHF antenna? Can they be in the same plane?"
AMD Phreak:
Go as far as you can, but more importantly run STP to the radios, that is if they are on the tower. Overall, it shouldnt be affected, I have experience with stuff being next to VHF, UHF, and high-power 900MHz paging and have not had any issues.
keefe007:
How close have you mounted to VHF? The problem is that this antenna is near 15/20 feet tall so it's hard to avoid. It is one of those whip antennas with little ears hanging off. I would be mounting 3 120 degree 2.4 sector antennas on a pole roughly 1.5 feet horizontally away from it.
sporkme:
Curious, what's the spectrum that ethernet uses (100MB FE)? Any harmonics from nearby transmitters to look out for (meaning, do any "common" VHF bands perhaps disrupt ethernet with one of their harmonics)?
AMD Phreak:
I think isnt it like 100MHz?
Personally I dont chance it. I use STP for all tower installs due to the fact of there is so much RF where our gear is.
The big sticks are hard to get away from. You just have to do your best. I can check with the RF engineer and see what he thinks, in the AM. It shouldnt be all too bad though. I have put some 4.9GHz equipment next (4' above) to a high power 900MHz transmitter (500 or some watts) and didnt have a problem
lutful:
Fast Ethernet transmission uses 125Mbps "raw" data rate which is carried in a 62.5Mhz "MLT-3" waveform.
There is not much VHF coming out of properly twisted portions of the cable - most noise is coupled in the small untwisted section near the connectors.
wispman:
One time I had an ethernet cable I put in at an install that ran across a desk and it went right by a police scanner. The scanner "keyed up" and was locked on something like 150-160mhz.
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