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Resources for Antenna and Station Grounding

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N0TZU, Mar 22, 2021.

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  1. WA7ARK

    WA7ARK Ham Member QRZ Page

    If you have an "antenna structure" (mast, tower, grounded vertical), it is prudent to put ground rod(s) within a few feet of the "structure", in addition to placing a ground-rod just before coaxes/control cables enter the house wall ("entry panel"). At that point, to satisfy code, another #6awg bonding wire should parallel the coax(es)/control-cables between the "structure" ground rods and the "entry panel" ground rod, then onto the electric utility ground. That should provide a conductive path all the way from the "structure" to the electric utilily ground that will prevent the coax cables from opening during the event.
    AK5B and W6KCS like this.
  2. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

  3. NM5TF

    NM5TF Ham Member QRZ Page

    Lightning is NOT your antennas' friend.....or your house electronics either....
    My house has been struck twice in the 30 years I have lived in it....1st time it
    hit a tree about 30 feet from house, went underground & entered house thru
    the power ground connection...took out telephone entry box ( blew the cover
    across the living room) a printer, wifi modem, and welded the SAT box to the DVR
    it was sitting on, etc....

    2nd time was more IMAX 2000 took a direct hit....even tho the
    antenna & mast had a ground rod right next to mast, and another ground rod
    where the coax enters the shack...the image shows the result.... imax-litning.jpg
    KX4O likes this.
  4. K1LH

    K1LH XML Subscriber QRZ Page

    The grounding system's goal is to keep the lightning on the outside of the building, protecting the human(s) on the inside and their equipment as much as possible. Wither or not your antenna gets vaporized is besides the point :) Since you'd done your grounding properly by the sounds, it likely saved your life and stopped your house catching fire.
    WA7ARK, KX4O and NM5TF like this.
  5. N1IPU

    N1IPU Premium Subscriber QRZ Page

  6. W2WDX

    W2WDX Premium Subscriber QRZ Page

    This is a methodology that applies to building construction, and not grounding for a radio station. It speaks to strike probabilities, not mitigating potentials.

    Case in point, say you have a tower 150" feet away from a building. The tower has its own ground rod and the house has it's own ground rod at the electrical panel. Now lets say there is ground strike somewhere between these two point. There is resistance between those two rods through the earth, a fairly high one is some circumstances. So you have some high voltages being introduced into the earth, maybe through a tree, and two ground rods on either side of those two big resistors. And of course, you have a coax cable from the antenna to the equipment in your home. So what do you have? A big voltage divider with the coax shield completing circuit. The two grounds now being at different potentials. The difference will travel on your coax shield, go through the radio gear and flow through the electrical panel ground. Even if you have a Polyphaser or similar device at the coax entry point you still will have a potential difference between the three ground points if they are not physically bonded. Multipoint grounding is only accomplished by having all the earthing points (rods) at the same potential by reducing resistance between them to what is practically possible, accomplished by physical bonding. An added benefit, if you you use bare solid wire or strap, is the energy involved has a larger area to dissipate into earth via the bonding length underground.

    Sphere Method only deals with the area where a strike probability can occur, not in dealing with potentials or mitigating any potential difference set up in an electrical/electronic infrastructure.
    Last edited: Sep 3, 2021
  7. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I agree, in my case the 195 foot tower will get hit 1st, then it all relies on the single point ground concept which all points must be at the same potential. Which is not all that easy to do, it takes a lot of work and testing

    K0UO Rhombic Antenna Farm is located at the Kansas QTH with over Two miles of Wire in the Air & On the Air, “The RF Gotta-Go-Somewhere", and in the above case so does the Lightning!!!!
    Last edited: Sep 3, 2021

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