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Re: [TowerTalk] book Tribander comparison test

To: "'Joe Subich, W4TV'" <lists@subich.com>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] book Tribander comparison test
From: "Dick Green WC1M" <wc1m73@gmail.com>
Date: Fri, 25 Feb 2011 02:21:30 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Yeah, but there's another variable besides forward gain, bandwidth and
feedpoint impedance: front-to-back ratio. The 3-el and 4-el SteppIRs have
only about 11 dB F/B on 10m, which is less than half the F/B of a 3-el or
4-el 10m monobander with optimized element spacing. I'm no antenna design
expert, but I have to believe this is due to the fixed element spacing. In
that sense, the SteppIR is more like a tribander than a monobander (c.f.,
the Force12 C3E, which has similar poor F/B on 10m).

Don't get me wrong -- I have a 3-stack of 4-el SteppIRs and love 'em! In
many respects they're like monobanders, but not in all respects.

73, Dick WC1M


-----Original Message-----
From: Joe Subich, W4TV [mailto:lists@subich.com] 
Sent: Thursday, February 24, 2011 8:33 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] book Tribander comparison test


 > It would be, if they had motors to vary the distance between the
 > elements

Nonsense!  Some 30+ years ago W2PV showed that a monobander was a
monobander no matter what the element spacing as long as the elements
are properly tuned for their place in the array.  Gain is a product
of boom length as long as there are "enough" elements for the length.

Tapered spacing only effects the bandwidth and feed impedance of the
antenna and with a SteppIR bandwidth has no meaning since the antenna
is constantly retuned for the operating frequency.

SteppIR is a tunable "monobander" with a fixed length boom - other
than the optional fixed length elements for six meters, a SteppIR
has no traps or parasitic elements whose sole purpose is to allow
operation on more than one frequency at a time.

73,

    ... Joe, W4TV


On 2/24/2011 6:57 PM, Dick NY1E wrote:
>   " As far as the SteppIR, it's a monobander for all  practical purposes."
>
> It would be, if they had motors to vary the distance between the
elements... otherwise its a tribander (ok 5 bander) with a good swr!
>
> Dick NY1E
> www.ny1e.com
>
>
>
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