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Re: [TowerTalk] Quad vs SteppIR

To: <>, "Bill Ogden" <>
Subject: Re: [TowerTalk] Quad vs SteppIR
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Mon, 30 Aug 2004 10:53:04 -0400
List-post: <>
> I am wondering if a 3 element SteppIR would provide any
> improvements in my situation.  The SteppIR is probably
easier to handle and
> the 180 degree switch appears to be a very nice feature,
but is this
> sufficient to justify switching?  Does anyone have
experiences about quad
> vs SteppIR?

Hi Bill,

This is all based on "how it works" data, not an actual
comparison. I've had quads and Yagis, and the SteppIR is
nothing but a Yagi.

If both your old quad and the proposed SteppIR antennas both
have reasonable efficiency, you can expect performance to be
roughly proportional to boom length, assuming the number of
elements is nearly optimum for any given boom length. This
means the SteppIR should at least equal if not actually
improve performance as long as it has a longer boom. My bet
is that it would actually improve your system a few dB for
both receiving and transmitting.

I almost hate to say this, but an occasional reminder is due
from time to time. A quad has no real gain advantage over a
similar size Yagi. The original "2dB" thing came from flawed
measurements of a scaled model by a W2 and W6 long ago, and
once it was in print that was took on a life of its
own. At some heights a small quad antenna can show a little
advantage (perhaps 1 dB) and at other heights a slight loss
over a similar boom length yagi. Overall they are about
equal, although for some reason long quads did not fair well
in actual measurements (Wayne Overbeck N6NB and Dave Bell
W6AQ, CQ Magazine, May 1982).

Another quad myth is capture area, but physical aperture is
not the same as electrical aperture or "capture area".
Capture area only relates to gain and frequency, so any
antenna with the same gain on the same frequency has the
same capture area! That's true if one is a big box, and the
other is a small single plane element. Capture area also
does not determine S/N ratio, so it a moot point anyway.

Directivity sets receiving, not gain or capture area (more
correctly called effective aperture). I would expect the
SteppIR to receive better, because it should have better
directivity. The exception might be in times of inclement
weather, since the quad generally has less of a corona
(P-static) problem. In the few quads I've had here, that was
the only advantage I ever saw when comparing them to similar
size Yagi's.

73 Tom


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