Industry Forums > Wireless Service Providers > Grounding and antenna diagram - appreciate comments

reply to chisel

Re: Grounding and antenna diagram - appreciate comments

Briefly...

The long LMR-600 will have losses totaling 8 dB, which is not great but manageable, provided the antenna and amp gain is sufficient. I'm presuming that the amp is bidirectional.

The antennas should be mounted as far apart as practicable to avoid pattern distortion, especially since the antennas are near integral multiples of wavelengths of the bands being used.

You should move the ground from pole to the first ground rod to the ground bar near the entrance to the house, and delete that ground rod (the one near the corner of the porch) so the ground conductor path is:

pole > entrance > service ground

Use bare #6 solid rather than stranded as it lasts longer in the ground. The lack of insulation is beneficial. The long ground should not be too close nor too far from the conduits as ground potential rise can be a problem. A foot is about right.

You should add three ~10 ft. 'radials' to the base of the pole to provide a superior ground as you want to give the lightning every opportunity to jump off there rather than travel down the wiring. Bury them as deep as the conduit.

If there is any risk of lightning in your area, you need to add a lightning rod to the pole at the top which can be a 4 ft. ground rod (Radio Shack) bonded to the pole and the rest of the grounding at the pole.

You need to add lightning arrestors to both the coax and the Cat5 at the pole in addition to the ones at the house. What kills equipment is not the high voltage, but the high voltage differential between the equipment, conductors and ground.

Oh, in your case...ignore my sig.
--
Don't ask questions -- just do as you're told.

This is essentially what you want.

I did this for another project (a taller tower) so it's a bit overkill for your situation, but the general idea is the same.

reply to John Galt

TYVM! I was editing my diagram to show what I thought you said.
Yes, lightning is a definite possibility since I'm in western KY, and ground wire is #6 solid bare.

I believe the 32 dB amp. (for the 4G connection) is bi-directional since it has both uplink an downlink dip switches. RSSI and SINR were -76 and 26 to 30 with no amp. and antenna 4' off the ground at the pole site. I was planning to run both the coax and Cat 5E in the same trench but in separate conduit. Will run ground 1' away.

So at the bottom of the pole keep the grounding bar and and do not attach it to a ground rod? Or skip the grounding bar and attach the arrestors to the ground wire running around the pole? How does this sound - attach ground wire to each antenna, run the wire down the pole and attach it to circular wire around base of pole.

I'll do what I'm told, no prob.

Since the pole is metal, you can bond the equipment at the top directly to the pole. The overall objective is to keep everything at the same potential, so if you wait to bond to the grounding at the bottom, the potential rise will cause the magic smoke to come out.

The inductance (essentially resistance) of the metal pole is far less than the wire you would run down the pole, so the strike will take that path rather than going down the wire.
--
Don't ask questions -- just do as you're told.

If I understand you correctly, bond the antennas to the metal pole, but do not connect a ground wire to the antennas and run it down the pole. Bond bottom of pole to buried ground wire as in your diagram.

After reading some comments here on DSLreports, I have decided to skip the LMR-600 and go with Andrew Heliax LDF4-50 assuming I can get it at a decent price. I have been researching cables and all of the various connectors...I don't see how you all keep it straight. It seems every brand and every size cable has a different prep. tool plus different ways to attach the connectors.

JG, thank you VERY much for your help.