Front to Back (or Front to Rear) ratio is something that the SteppIR type
beam will excel at. Also, the SteppIR concept allows you to free one of the
parameters that otherwise you'd have to optimize: bandwidth. You can set
the SteppIR up for performance at a single frequency.
As an interesting exercise try something I inadvertently found out about the
other day. Take almost any 3 element 20m beam that has been optimized for
gain or F/B at a particular frequency. Run a series of patterns at 100 kHz
steps covering from, say, 13.9 to 14.5 MHz. Ignore the change in Z, and
look at the gain (which doesn't change with the reactive part of feedpoint
Z) The gain won't change all that much, but the back lobes change
dramatically.
I suspect that for the vast majority of situations, the beam works better
than the dipole or omni because it suppresses the stuff off the back and
sides, not because it ekes out an additional 3 dB of gain.
----- Original Message -----
From: "Jerry Keller" <k3bz@arrl.net>
To: "Ward Silver" <hwardsil@centurytel.net>; "Towertalk Reflector"
<towertalk@contesting.com>
Sent: Wednesday, September 10, 2003 5:38 PM
Subject: Re: [TowerTalk] Short Booms
> The 3 element SteppIR has only a 16 foot boom, yet has achieved a strong
> following of users who think it's the best thing since the yagi was
> invented. I can't do the math, but it would seem that tuned elements are
> more important. Comments? Jerry K3BZ
>
> ----- Original Message -----
> From: "Ward Silver" <hwardsil@centurytel.net>
> To: "Towertalk Reflector" <towertalk@contesting.com>
> Sent: Wednesday, September 10, 2003 8:11 PM
> Subject: [TowerTalk] Short Booms
>
>
> > > No amount of clever engineering in areas of element interaction, feed
> > > efficiency, tuning networks (i.e. - traps), impedance matching
gadgetry,
> > > etc. can make up for a short boom.
> > >
> > > True?
> > >
> > > 73 - Bryan W4WMT
> >
> > In terms of raw forward gain, true, but short-boom antennas can be
> designed
> > to manage the bedeviling secondary factors in ways that make them better
> > antennas than poorly implemented long-boom antennas. Antennas are
complex
> > critters with a lot of parameters to consider - bandwidth,
front-to-back,
> > SWR, feedpoint impedance, and mechanical robustness - that require
> > compromises in gain. In determining bang for the buck, one has to
define
> > "bang" pretty carefully.
> >
> > 73, Ward N0AX
> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any
> questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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