[Antennas] Radials

Sat Apr 18 08:59:06 EDT 2015

Thanks, David.

I live pretty close to what a lot of people call the lightning capital of the U.S.A. I have never heard of a tower base being exploded by lighting, out of the myriad stories of stations being hit. The Ufer isn't intuitive, I had a hard time accepting it, but I fully embrace it now!

Yep, the 80M sloper is as you describe. i'll get some more wire down and see if I can get more than 600 mikes or so out of the inverted-L.

73, Mike NF4L

> On Apr 18, 2015, at 08:44, David Robbins <k1ttt at arrl.net> wrote:
> 
> 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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