[Antennas] W4HDX Zepp antenna query

[D.J.J. Ring, Jr.]

108 feet on each side total 216 feet for 80 to 10 meters fed with feeder of
two 50 ohm coax runs with braided shields connected together at the center
fed doublet of 108 feet each side, dual coax run has braids likewise
connected to each other at the transmitter end and grounded to the station
ground.

Antennas do not have to be resonant to work.  This antenna was designed to
avoid resonances on purposes.

Prior to 1970 most transmitters could load random wire antennas which
worked very well especially if up high and in the clear.  No feed lines
needed, just bring wire to transmitter.  Or use low loss feed line like in
zepp antennas.

W4HDX just used coax cables like old fashioned zepp feeder.

You want a one band antenna?  Then match impedance and make resonant.  It
will out perform this antenna easily.

73

David
On Jan 3, 2015 7:33 PM, "JOJ006 Mail" <joj006 at gmail.com> wrote:

> Hi - my first posting here I believe. I wonder if anyone on this forum has
> simulated or built the W4HDX Zepp antenna? The original publication can be
> found here and other places...
> http://www.southslope.net/~kb0sk/img/zepp.pdf
>
> He claims low noise pickup with good performance and easy ATU matching by
> designing the top to be flat  or non-resonant on any of the intended bands
> and he uses a double coax feed with the balun at the sending end of the
> twin feeder arrangement rather than at the antenna.
>
> I'm puzzled as I would have intuitively thought that for an antenna to
> radiate efficiently, it would need to be resonant on the intended bands. I
> assume that the twin coax feed is a matching section but he says it can be
> any long length over a certain minimum rather than a quarter wave etc. and
> can even be buried so it's not expected to radiate as, for example, a
> Windom feeder would.  In fact a quarter wave has to be avoided.
>
> Is it that the ATU is part of the antenna resonance, as it might be for
> example with an end fed long wire, rather than it being a simple impedance
> matching device?
>
> I'm trying to get my head around this one.  If it was really that good I'd
> set about making a Carolina Windom version to suit the geometry of my site,
> but I'm sceptical.
>
> What do others think and has anyone simulated it?
>
> Thanks, John, ei1em/g3vlo
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