Topband: Multiple Ground Systems

[Richard (Rick) Karlquist]

Tom Rauch wrote:
>> I have always disbelieved the "bond the crossing radials" 
>> old wives tail, for good electrical reasons... These 
>> crossing radials have differing RF phase and voltage on 
>> them... Bonding them together is a short circuit causing a 
>> lump in the radial field pattern...
>>  Case in point:
>>  About 10 years ago I had a 4 element, 160 array with 8 
>> elevated radials under each vertical - the array was 
>> parasitic not an all driven... Of course the elevated 
>>  >radials crossed each other but they were
>>     
> < Snip>
>
> What that proves  more than anything  is the radials in a 
> small elevated radial system are significant nearfield 
> radiators and not "grounds". It simply proves the fields are 
> very concentrated near the wires and are not "spread out" 
> and are not low level near each radial like they are in a 
> conventional or large ground system.
>
> It doesn't relate or apply at all to use of a common buss 
> along the area bisecting adjacent radial fields.
>
> In truth, other than work or money, there is very little 
> difference between isolating and laying radials in a 
> straight line radially in a multi-element array and using a 
> large buss at a point bisecting the pattern of the elements 
> when the ground system is doing its job and isn't part of 
> the . All those BC stations all those years weren't all that 
> dumb, they knew what they were doing. The system they used 
> worked very well and caused no problems as applied to a 
> non-resonant ground system.
>
> The other way would work also, just keep the wires bonded or 
> isolated.
>
> I wouldn't expect bonding to work in a system that has very 
> intense voltages and currents on each radial.
>
> 73 Tom
>
>
>
>
>
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>   
Here is something I always wondered about.  Let's say you have verticals 
spaced
1/8 wave.  A radial from one vertical headed towards the other is 1/16 
wave long.
When it hits the "bus" wire, it simply sees a continuation of itself for 
another 1/16 wave
toward the other vertical, and then it continues on on the other
side of that vertical.  So far so good.

Now imagine radials at 45 degrees away from the other vertical.  They 
are almost
3/32 wave long, but meet at the bus wire at a right angle.  In that 
case, a radial doesn't
see an extension of itself, but rather an array of radials at right 
angles that can't
carry any current in the direction needed.

How does all this jibe with the canonical 1/2 wave broadcast radials?

Rick N6RK