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Walter Maxwell · September 27th 06, 05:10 PM posted to rec.radio.amateur.antenna

On Wed, 27 Sep 2006 04:40:51 -0000, (Dave Platt) wrote:

In article ,
John E. Davis wrote:

The elevation pattern of the antenna shows a hint of the high-angle
secondary lobes which characterize an EDZ.

This is definitely noticable on a log plot.

So, I'd conclude that you've developed a variant on the EDZ (or
something partway between an EDZ and a center-fed fullwave) which
yields slightly lower gain than an EDZ but has a simpler matching
section.

What sort of gain is expected from an EDZ? I tweaked the topology
of my design a bit in the hope of getting a broader bandwidth, but
instead got even more gain. For example, the version represented
below has a minimum gain of more than 4.7 dBi (at the side) and more
than 5.25 dBi in the forward direction. Previously I reported gain
values that ran from 4.2-4.7 dBi. So this one represents a bit of an
improvement.

For an EDZ in isolation (no mast) I believe it's around 3 dBd or 5
dBi, plus or minus a hair.

I modelled a copper-pipe EDZ, mounted at the top end of a conductive
mast. This one came out with 5.85 dBi in the favored direction, and a
2.5 dB front-to-back ratio.

Have I missed something here? As I understand the EDZ (is it not the Extended
Double Zepp?) it comprises a center-fed doublet with a 5/8 wl wire on each side
of the feed point. It's broadside gain is about 3.1 dBd, with a narrower lobe
than that of a dipole, from which the gain over a dipole is obtained. Am I
correct so far?

If so, then we have only a single radiator. How then can there be a
front-to-back ratio?

Walt,W2DU