[Hi-zreceivingarraydiscussions] Grounds for 4 square

[Lee STRAHAN]

Hello Craig,
   Nice to hear from you. The URL for posting to the Hi-Z reflector is a little different than what you used. I suspect that is the sign-up URL. Here is the correct one.  Hi-Z Group   (Hi-zreceivingarraydiscussions at hizantennas.com<mailto:Hi-zreceivingarraydiscussions at hizantennas.com>)  .
   In regard to the grounding I would say the use of the rusted steel would be totally dependent on the moisture in your soil. In my case I have used the same steel posts for many years. They are seriously deteriorated but I believe that they are still functioning correctly because I have fertile farm ground for the arrays. The other thing that happens with steel is there is a small voltage difference between shack ground and the element grounds  due to the voltage drop in the connecting wires. I feel that this difference in potential is causing the galvanic deterioration to accelerate. I suspect in dry ground the rust would not be the best ground situation.
    That all being said the fact remains that you cannot have too much ground for the elements and so one can add 1 or more copper ground rods or pipes, you can put metal plates in the ground, and you can use a chicken wire type mesh, and you can use radials. Some with radials have eventually removed them as they were not helping the performance of an array. Some have added them and helped the performance of an array. It remains that it is dependent on the soil or lack thereof. The one very important thing beyond the actual resistance value of the ground in use is that all the verticals share the same construction closely.
Here are some numbers from a computer simulation of phase and amplitude changes due to ground resistance.
  From 10 ohms to 50 ohms there is essentially no change in element output level. There is 0.32 degrees of phase change.
  This is no problem for any of the Hi-Z arrays.
  From 60 to 100 ohms there is only 0.2 dB voltage change but an additional change of 0.32 degrees phase shift.
   Going from the 100 ohms down to 10 ohms begins to be an appreciable phase change in element output with the voltage output remaining nearly constant. This is only where there is a difference in ground from one element to another  that the array is affected.
   It is where the ground resistance approaches the next 100 ohms change where the array begin to get into trouble. Going from 100 ohms to 200 ohms ground rod resistance yields a full 0.69 degrees phase change and the output level remains nearly constant within 0.2 dB.
    And going from 200 to 300 ohms the phase changes another 1.6 degrees which is a disaster with a difference as large as this between elements plus there is appreciable voltage loss  of .03 dB. An array with mixed ground resistance of this magnitude would be seriously compromised.
   So I conclude that if you can get all the elements below 100 ohms or so of Very low frequencyground resistance between all elements you should be be fine with the Hi-Z arrays. This says nothing of the dielectric constant of the ground however the resistance value should dominate and leave you with excellent performance. Measuring the ground resistance is a problem of its own as was recently discussed on the top-band reflector.
  I would certainly be interested in all comments from users that may have experimented with this.

Lee K7TJR
Hi-Z Antennas



From: Craig Clark [mailto:jcclark at myfairpoint.net]
Sent: Sunday, December 11, 2016 12:27 PM
To: k7tjr at msn.com
Subject: Fwd: Grounds for 4 square

I posted this a Friday but it never showed up on the reflector
Thoughts?

CraigK1QX
Sent from my iPad

Begin forwarded message:
From: Craig Clark <jcclark at myfairpoint.net<mailto:jcclark at myfairpoint.net>>
Date: December 9, 2016 at 09:12:01 EST
To: hi-zreceivingarraydiscussions-request at hizantennas.com<mailto:hi-zreceivingarraydiscussions-request at hizantennas.com>
Subject: Grounds for 4 square
I have been using 4' L shaped steel for mounting my elements. I am also using them for the grounds as my array can only be installed after farming is done. As we all know, steel rusts and that may effect performance.

I could install copper pipe grounds but the can't be more that 1-2' long.

Thoughts?


CraigK1QX
Sent from my iPad