[TowerTalk] Rai Beam
wa4dou@juno.com
wa4dou@juno.com
Tue, 11 Apr 2000 17:19:43 -0400
Mauri,
Respectfully, i'll have to disagree with you. I've seen few cases where
3 db would have done anything for me. I work mostly cw, and occasionally
work signals in the noise. Furthermore, i'm a qrp'er, running mostly 5
watts and under. 3 db is not much gain. I challenge you and all other
list subscribers to obtain a step type attenuator, install it in line,
and switch it in and out in a variety of situations. Except in the noise,
3 db will not make or break your communications. And if i do miss the dx
today, it will be back tomorrow. 5 watts is 13 db down from 100 watts and
23 db down from 1000 watts. Propagation is a great leveler of signals. 73
Roy WA4DOU
P.S. You are right, gain is a direct function of boom length. Thats an
entirely different subject.
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On Tue, 11 Apr 2000 10:49:12 +0200 "i4jmy@iol.it"<i4jmy@iol.it> writes:
> It depends by the S/N situation, but in most cases a 3dB gain is a
> lot,
> "to hear or not to hear".
> Stated it, the gain in yagis is a direct function of boom lenght.
>
> 73,
> Mauri I4JMY
>
>
> > ---------- Initial message -----------
> >
> > From : owner-towertalk@contesting.com
> > To : towertalk@contesting.com
> > Cc :
> > Date : Mon, 10 Apr 2000 14:05:30 -0400
> > Subject : Re: [TowerTalk] Rai Beam
> >
> >
> > Hi Joe,
> > Reviewing a few known facts, i remember that the ZL Special, a
> dual
> > driven
> > phased array, has a gain of about 3 dbd. The 2 element yagi
> produces a
> > gain
> > of 4.5-5 dbd, the 2 element quad produces a gain of 5-5.5 dbd, the
> 3
> > element
> > yagi produces a gain of about 6 dbd, the 4 element yagi- about 7
> dbd,
> the
> > 5
> > element yagi- about 8 dbd, so on. Beyond about that limit, the
> gain
> > starts to fall
> > below 1 db per element.
> > I don't believe for a second, that the 2 element Raibeam
> produces a
> > gain of 8
> > dbi, which translates into 5.9 dbd., but for the sake of the
> arguement,
> > lets assume
> > that it does, for a moment. (Does anyone know how the Raibeam
> differs
> > from
> > the ZL Special?).
> > First and foremost, the advantage that one enjoys with most
> antennas
> > with
> > directional characteristics, it that they are raised to a height
> that
> > places their
> > lower lobe in the range of angles of radiation that are
> appropriate
> to a
> > particular
> > path. Even a dipole would perform well under such circumstances.
> Its
> > therefore,
> > not surprising that "trapped" tribanders with typical gain figures
> of
> > 1-1/2 to 3 dbd
> > would also perform well. Likewise, the ZL Special, 2 element
> yagis,etc.
> > The
> > differences between all these antennas are only a few db. Without
> a
> > reference
> > antenna for comparison, most of us would be hard pressed to even
> know
> > that there
> > was a difference, except intellectually. A difference of 1 db is
> so
> > insignifiicant that
> > even under closely and carefully controlled conditions, most of us
>
> could
> > only just
> > barely discern that level of difference between two signals. A
> difference
> > of 3 db isn't
> > remarkable( to quote Bill Orr), 5 db is a worthwhile difference
> (again, to
> > quote Orr),
> > and a difference of 10 db, is a new level of performance, but
> still
> only
> > the difference
> > between an s-9 signal and one 10 db above s-9, IF, the "S" meter
> is
> > accurately
> > calibrated.
> > I will continue this in PART 2. 73 for now, Roy Lincoln WA4DOU
> >
> ----------------------------------------------------------------------
> ---
> > ----------------------------------------
> >
> > On Mon, 10 Apr 2000 19:14:38 -0400 Joe Reisert <jreisert@jlc.net>
> writes:
> > >
> > > To Interested Antenna Buffs,
> >
> > >
> > > 2. If it is true gain, we better all dump our antenna software,
> get
> > > a
> > > Raibeam and take down those big beams we are now using. Greater
> than
> > > 8 dBi
> > > gain in "free space" on 2-element a tri-bander using only an
> eight
> > > foot
> > > (0.12 wavelength on 20-meters) boom is mighty impressive.
> > > Furthermore the
> > > pattern in the ad infers a F/B ratio of almost 30 dBs!
> > >
> > > Is this antenna patented? If so, what is the patent number so I
> can
> > > get a
> > > copy and be enlightened.
> > >
> > > I'm anxiously awaiting the new antenna gain theory!
> > >
> > > Joe, W1JR
> >
> >
> > ________________________________________________________________
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> > --
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> >
> >
>
>
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