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chisel
Premium
join:2009-09-01
Henderson, KY

Grounding and antenna diagram - appreciate comments

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I have spent a week reading through this forum trying to learn as much as possible and would appreciate constructive comments about my proposed antenna installation. I have not set the pole yet, but that is the best place for it to get good reception from Verizon as there are trees and power lines btw. the pole and the house.

2 yagis on 1 pole...will they interfere with one another? I could separate vertically 5 ft. if that helps.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
What devices are mounted on the pole?

What is the coax for?

chisel
Premium
join:2009-09-01
Henderson, KY
Mounted on the pole will be a Yagi antenna for Verizon 4G reception and a Yagi for 900 MHz wireless ISP reception. Coax is needed for the 4G and Cat 5E for 900 MHz.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
Are there active electronics at the pole for the 4G, in other words more hardware than just the antenna feeding the coax?


Inssomniak
The Glitch
Premium
join:2005-04-06
Cayuga, ON
kudos:2
reply to chisel
175++ feet of coax for the 4g antenna is gonna be very lossy. Are you running very heavy duty coax for that?

Might be best to keep the electronics at the pole for that 4g service and run 2 cat5s instead.
--
OptionsDSL Wireless Internet
»www.optionsdsl.ca

wirelessdog

join:2008-07-15
Queen Anne, MD
kudos:1
reply to chisel
What does this topic have to do with running a WISP?

That said, unless you are running a 4g amp your coax run is way too long.

chisel
Premium
join:2009-09-01
Henderson, KY
reply to John Galt
Sorry I wasn't more clear - nothing active on the 4G antenna, just the coax feeding it. Will have an amp. in the house for that setup. For the 900 MHz yagi, there is more than just the Cat. 5 feeding the antenna - there is a device just below it. The Cat. 5 comes in the house and feeds into a small Cat. 5 dongle-type thing with a/c power going to the dongle. So I assume some small voltage goes back out to the antenna...at least that's what the installer said. I can take a pic of the antenna tomorrow and post. Coax, Cat. 5 and ground wire will be going up the pole.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
What type or size of coax is it?

chisel
Premium
join:2009-09-01
Henderson, KY

1 edit
reply to wirelessdog
I know, but the experts seem to be in here, and since I have 2 wireless services, I thought you all might be willing to advise me. I did not see another forum that had the depth of knowledge as this one. My apologies....I did not mean to step on any toes. Can you suggest another forum? I will ask the mods to move the thread.

I was planning to run LMR-600 for the coax with an amp.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
You're fine...don't worry about it.

Now that we have the information we can offer some suggestions.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8

1 recommendation

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.



John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
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.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
reply to John Galt
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.

chisel
Premium
join:2009-09-01
Henderson, KY

1 edit
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.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8

1 recommendation

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.


chisel
Premium
join:2009-09-01
Henderson, KY

1 recommendation

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.