[amsat-bb] When exactly is a non-conductive mast necessary?

[Andy]

I used a copper boom for many years.
The antennas were oriented in an "X" pattern.
The vertical mast was aluminum.
Several thousand satellite contacts later, what can I say?
If it works, use it.
Have a polarization switch on 70cm. You need it.
And yes, pay attention to connectors and coax!

Andy W5ACM

-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of John Kludt
via AMSAT-BB
Sent: Monday, December 30, 2019 8:21 PM
To: Cathryn Mataga <cathryn at junglevision.com>
Cc: amsat-bb at amsat.org
Subject: Re: [amsat-bb] When exactly is a non-conductive mast necessary?

Cathryn,

And if you pay attention to all of the caveats in his paper.  One saving
grace about all of this is it is not EME.  If you were working with
250 +/-  dB path loss and a passive reflector like the moon you might come
to a different conclusion.  Just be careful of all of the those 1/2
wavelengths and 1 wavelengths that he speaks about.  Especially for the 70
cm uplinks as that isn't very many inches.

The other thing I have seen folks trip over is coax selection.  Satellites
are not the place to be using RG-8X.  Others may have other thoughts I think
you are looking at LMR400 or its equivalent or better if it is a permanent
installation.

John


On Mon, Dec 30, 2019 at 7:57 PM Cathryn Mataga via AMSAT-BB <
amsat-bb at amsat.org> wrote:

> Oh, thanks guys. This is eye-opening.  It looks like even circular 
> polarized antennas will work with metal masts, if you rotate them 45 
> degrees.
>
>
> On 12/30/2019 2:31 PM, Gary wrote:
> > The short answer is almost never. Here is a link to an AMSAT 
> > Symposium
> paper form antenna guru Kent Britain, wa5vjb (inventor of the famous 
> cheap yagis). He actually measured the effects.
> > http://www.kk0sd.net/metalboom/metalboom.htm
> >
> >
> > 73,
> > Joe kk0sd
> >
> >
> > -----Original Message-----
> > From: AMSAT-BB <amsat-bb-bounces at amsat.org> On Behalf Of Cathryn 
> > Mataga
> via AMSAT-BB
> > Sent: Monday, December 30, 2019 3:27 PM
> > To: amsat-bb at amsat.org
> > Subject: [amsat-bb] When exactly is a non-conductive mast necessary?
> >
> > I'm trying to understand, under what circumstances is a 
> > non-conductive
> mast necessary at VHF/UHF frequencies. Thinking of the following installs.
> >
> > 1.  Circular polarized antenna mounted to the mast at the center of 
> > the
> boom.    This is clear, see this advice all the time, fiberglass mast.
> >
> > 2. Same antenna but mounted at the rear end of the boom.
> >
> > 3.  Vertical Yagi, elements parallel to a vertical mast, mounted at 
> > the
> center of the boom. I guess, non-conductive wold be required here.
> >
> > 4.  Same antenna but rear mounted.
> >
> > 5.  Horizontal Yagi, elements perpendicular to a vertical mast, 
> > mounted
> at the center of the boom.  I think this is pretty normal install, so 
> a conductive mast would be okay?
> >
> > 6. Same antenna but mounted at the rear of the boom.
> >
> > _______________________________________________
> > Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum 
> > available
> to all interested persons worldwide without requiring membership. 
> Opinions expressed are solely those of the author, and do not reflect 
> the official views of AMSAT-NA.
> > Not an AMSAT-NA member? Join now to support the amateur satellite
> program!
> > Subscription settings: 
> > https://www.amsat.org/mailman/listinfo/amsat-bb
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available 
> to all interested persons worldwide without requiring membership. 
> Opinions expressed are solely those of the author, and do not reflect 
> the official views of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
>
_______________________________________________
Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available to all
interested persons worldwide without requiring membership. Opinions
expressed are solely those of the author, and do not reflect the official
views of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb