Advice on lightning protection for a VHF/UHF base antenna installation

[AFSOC]

Looking for some advice from some old shoe amateurs to fill in some sizable knowledge and experience gaps in my UHF/VHF know how. I just moved into a house and intend to put an antenna mast on my roof for a vertical VHF/UHF base antenna. I have tentatively selected a location for the antenna, eyeballed a good direct run from the mast to a ground rod location and have estimated a path/distance/ground rod quantities to tie into service ground. My questions have to do with grounding and bonding as it applies to lightning protection but I of course will accept any advice on RF grounding as it relates to my 2M/70cm station.

I want to set up my station in my garage which is on the opposite end of my home structure from my service panel and ground. I am unable install a perimeter ground due to a 32 ft wide concrete slab in front and a 36 ft wide slab in back for the pool deck, both butt up too and terminate at the house foundation. I can bond my antenna mast ground to the service ground with 40 ft of 4ga solid and three rods along the run. My biggest question is how to bond the ground rod attached to my coax/Polyphaser to the service ground? Does it even need to be bonded to service ground? Can I just run a bond wire from the ground rod to the home circuit breaker panel (located in the garage)?

Any advice is appreciated. I live on the gulf coast of Florida and we're no strangers to lightning here.

 

[DaveInDenver]

You would have to bond the lightning and grounding electrode system together. I think driving another ground rod(s) near your shack is probably the best way to do it and then tie them together with another ground conductor to keep them at the same potential. Your power neutral and ground is at the service potential and you don't want a ground potential to form with the radio case tied to RF ground or antennas. In reality lightning protection is just static protection, no ground or polyphaser is going to absorb a direct hit. So you need to be safe the other 99.99% of the time and not get shocked by touching your radio.

You'll want to put the polyphaser mounted on a copper plate right on the ground rod nearest to your shack feedline entrance. You can connect your station ground with copper braid or wide, thin copper sheet.

Maybe put them in a box like this.

 

[AFSOC]

You would have to bond the lightning and grounding electrode system together. I think driving another ground rod(s) near your shack is probably the best way to do it and then tie them together with another ground conductor to keep them at the same potential. Your power neutral and ground is at the service potential and you don't want a ground potential to form with the radio case tied to RF ground or antennas. In reality lightning protection is just static protection, no ground or polyphaser is going to absorb a direct hit. So you need to be safe the other 99.99% of the time and not get shocked by touching your radio.

You'll want to put the polyphaser mounted on a copper plate right on the ground rod nearest to your shack feedline entrance. You can connect your station ground with copper braid or wide, thin copper sheet.

Maybe put them in a box like this.

Thank you for responding Dave. I appreciate advice from such a knowledgeable source. I sent you a PM asking a couple of questions for clarification. I don't want to proceed if my assumptions are faulty.

Again, thanks for the mentoring.

 

[Big_Geek]

Most commercial installations use antennas from Decibel Products. The reason for this is that they are primarily a grounded design and have an incredible amount of lightning protection built in as most of the energy will travel to ground without passing through your delicate radio equipment. You will still want to use an in-line (and properly grounded) lightning arrester to help protect your radio, but the proper antenna will make a big difference for you. One of the problems with the high-gain fiberglass verticals is that they have some active components that will fail upon being struck by lightning and the entire antenna has to be replaced (in addition to your lightning arrester on the ground). This is, unfortunately, something you usually have to learn through expensive experience. The Decibel antennas are getting hard to find and they are expensive, but like many things in life, quality does not come cheap.

Good luck!

 

[Big_Geek]

Most antennas designed for mast mount will usually be designed to ground through the mast as well as the coax. Ground your mast extremely well. 40' is way too far to travel for this ground as lightning will likely prefer to pass through a bit more air and concrete - likely splitting it) to get to ground before traveling that distance over a wire. I like as many ground rods driven as deeply into the earth as close to the mast as possible and tied in to the mast with massive copper cabling.

My advice - take a lot of time to think, do as much research (including talking to local repeater operators) and plan your installation carefully. You will be glad you did when you're not having to fix it every other week.

 

[rambrush]

I also do the same thing, have the Alpha delta version instead of poly phasers just outside the house. I put in a ground rod there as well but then connected it back to the main ground rod as well it runs into the house for the main grounding buss. I use a antenna switch that when things are not in use it is switched to comm position to assist in keeping things from happening to radios.

 

[AFSOC]

Most antennas designed for mast mount will usually be designed to ground through the mast as well as the coax. Ground your mast extremely well. 40' is way too far to travel for this ground as lightning will likely prefer to pass through a bit more air and concrete - likely splitting it) to get to ground before traveling that distance over a wire. I like as many ground rods driven as deeply into the earth as close to the mast as possible and tied in to the mast with massive copper cabling.

My advice - take a lot of time to think, do as much research (including talking to local repeater operators) and plan your installation carefully. You will be glad you did when you're not having to fix it every other week.

Big Geek, Thanks for the reply. Maybe you misunderstood my mast grounding. I am driving an 8' rod directly under the mast. The 40ft, #4 bare is to bond the antenna ground electrode to the service ground. I will be driving an 8' ground rod every 12'-16' alond that 40 foot run.

 

[GlennA]

Most of our antennas are between 200 and 500 ft AGL. We mount a copper grounding plate in the building at the transceiver location. Connect the mounting rack/transciever to the grounding plate with #2 copper wire. Connect the grounding plate to the tower ground with 00 copper wire. Mount the polyphaser to the grounding plate. Attach a grounding kit to the coax near the bottom of the tower and ground the coax to the tower. Usually we have 3 or 4 ground rods driven into the ground with 00 copper wire cad welded to and connecting all rods, then attached to the legs/base of the tower. In a few locations, we have a halo (#2 copper wire full circle around the radio room attached to the grounding plate). I have not observed that the halo helps. We do not tie into the commercial power ground. We use high quality surge protectors from Panamax to help with strikes on the power side. You can substitute mast for tower. Most of our radios are on 24/7. Others are only activated during emergency conditions. They are physically disconnected from the antenna and power when not in use. The most important advice I can give you is to disconnect the antenna and power when not in use.

 

[kb9yoj]

Here is a 3 article series about amateur radio station grounding techniques. I have used these for my own setup.

http://www.dxengineering.com/techar.../lightning-protection-for-the-amateur-station


Matt
KB9YOJ

 

[jamesandrews]

If you still find it difficult to complete the antenna installation then checkout,http://sydneyantennas.com.au/,