[Antennas] Radials

[David Robbins]

I was responding more to the safety part of it and the exploding foundation
myth than about the inverted L.

A sloper for 80m if built the way I expect slopers to be built is really a
dipole with one end being the top of the tower... normally it's a 1/4 wave
wire hooked to the center of the coax pulled out from the tower with the
shield of the coax connected to the tower which forms the other half of the
dipole... that will not benefit from radials.

The inverted L will of course require as many radials on the ground as you
can afford.  Yes, they could be connected to the 3 radials that exit the
foundation with no problem.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net


-----Original Message-----
From: Antennas [mailto:antennas-bounces at mailman.qth.net] On Behalf Of Mike
Reublin NF4L
Sent: Saturday, April 18, 2015 12:32
To: David Robbins K1TTT
Cc: ANTENNAS-Mailman
Subject: Re: [Antennas] Radials

Thanks, David -

The question really really really was not about safety grounding, it was
about the RF return path(ground) for the 160 & 80M antennae as described in
the OP.

73, Mike NF4L

> On Apr 18, 2015, at 06:54, David Robbins <k1ttt at arrl.net> wrote:
> 
> Your electrician is right, don't bother with more radials or added 
> ground wires.  I would bury the radials you have, but just because I 
> would hate to waste the wire, but they aren't going to help 
> significantly for electrical safety or lightning protection.  Leaving 
> them on the surface definitely won't help either case, for electrical 
> safety or lightning protection you want radials buried as deep as 
> possible to provide them the most volume to dissipate any current they 
> carry. Putting them on the surface is the worst case as they lose half 
> the volume to start with since they can't dissipate charge into the 
> air and they have poor contact with the soil.  If you bury them at 
> least a few inches down they at least get better contact with the soil 
> but still only have about half the effectiveness they would have buried
3-4' down.
> 
> As far as for an rf ground, surface radials would help efficiency if 
> you were going to feed the tower as a vertical, but then you would 
> want many more than 3 and near the surface instead of buried.  Surface 
> or buried radials will not help inverted V's or Yagis.
> 
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
> 
> -----Original Message-----
> From: Antennas [mailto:antennas-bounces at mailman.qth.net] On Behalf Of 
> Mike Reublin NF4L
> Sent: Saturday, April 18, 2015 00:04
> To: antennas at mailman.qth.net
> Subject: [Antennas] Radials
> 
> I have a 70' tower with an inverted-L for 160M and a 1/4 w sloper for 80M.
> The tower base has 8 yards of concrete and a lot of rebar. There are 3 
> #4 copper wires, with one end attached to each tower leg, then into 
> the concrete, attached to the rebar then exits the concrete just under
ground.
> 
> The original plan was to put 3 ground rods along each wire. My 
> electrician told me that as far as safety grounding goes, there was no 
> benefit. The tower/base megged at 4 ohms.
> 
> The wires are currently rolled up at the base of the tower. If I 
> straighten them out and staple them to the lawn, do they then act as 
> radials? Would it be feasible to attach more radials to these where 
> they emerge from the concrete, so as to avoid having the top of the
concrete pad awash in wire?
> 
> 73, Mike NF4L
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