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Re: Cross Boom



Hello Everybody,

Dom,  your comment is spot on.  I don't see how anyone can expect to insert
a conductive boom into the rotating electro magnetic field and expect it not
to have any effect on the radiated wave, regardless of x or + element
orientation.

73 de Ken - K5GUU

----- Original Message -----
From: "i8cvs" <domenico.i8cvs@tin.it>
To: "Roy Welch" <rdwelch@swbell.net>; "hasan schiers" <schiers@netins.net>
Cc: "AMSAT-BB" <amsat-bb@AMSAT.Org>
Sent: Friday, March 07, 2003 12:19 AM
Subject: R: [amsat-bb] Cross Boom


> Hi All,
>
> Mounting a crossed yagi for CP in X or + configuration over a metallic
> boom produces the same effect over the circularity.
>
> When two crossed dipoles are feed by the same amount of power but their
> components are 90 degrees out of phase the resultant vectors of voltage
> and current rotates by  2 x 360 x f  every second producing CP
>
> The rotor of a AC sincronous motor rotates by the same phisical principle
> of magnetic rotating field discovered by Galileo Ferraris.
>
> Try now to put your finger in to the squarrel cage of the motor in both
> X or + position and see what happen to it !
>
> Your FINGER or your METALLIC boom are the same thing.
>
> 73" de i8CVS Domenico
>
> ----- Original Message -----
> From: Roy Welch <rdwelch@swbell.net>
> To: hasan schiers <schiers@netins.net>
> Cc: <amsat-bb@AMSAT.Org>
> Sent: Thursday, March 06, 2003 9:54 PM
> Subject: Re: [amsat-bb] Cross Boom
>
>
> >
> > hasan schiers wrote:
> > > I participated in the original discussion of this many months ago and
I
> > > think that the article referred to is being "under quoted". It is NOT
> just
> > > mounting the antenna in the "X" configuration. That is NOT what the
> article
> > > says. It also REQUIRES careful placement of the driven element
distance
> to
> > > the cross boom. Doing the "X" alignment is a "necessary" but not
> > > "sufficient" condition to get the results that the article claimed.
> > >
> > > Two conditions have to be met:
> > >
> > > 1. X configuration
> >
> > The article does say this.  Mounting the elements in a + configuration
can
> > "see as much as a 10db loss in gain and the circularity would be nil."
> >
> > > 2. Distance from the feed to the cross boom
> >
> > The article does say to avoid mounting the boom 1/2 or 1 full wavelength
> > from the driven element.
> >
> > As a third requirement the article says to "saw off any excess cross
> boom."
> >
> > I think I said all three of these in my original reply.
> >
> > > Many people have testified anecdotally to the metal cross boom
working.
> The
> > > work of the WA5 in the article made careful measurements. I wouldn't
> > > hesitate to try it, but follow the instructions in the article
> assiduously.
> > > The half-baked representations I have seen discussed lately are
unlikely
> to
> > > produce the "tenths of dB" performance hit described by the original
> author.
> >
> > The author's test was done about 1993. I have used this configuration
> since
> > 1981 or 1982.  It has worked fine here and I have had reports of it
> working
> > fine for others.
> >
> > > My comments aren't to discourage the metal cross boom approach. The
> article
> > > convinced me. However, let's not forget the second requirement.
> >
> > I didn't omit the second requirement.
> >
> > > ...hasan, N0AN
> >
> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT member? Join now to support the amateur satellite program!
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
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