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[aprssig] RE: 6m meteor Scatter project (radios&ants)

Robert Bruninga bruninga at usna.edu
Thu Jan 3 14:54:14 UTC 2008


> Ah yes the long wire...
> Or of course you could dig in a ground and 
> terminate in a 150-300 ohm resistor at the 
> far end.. 

My design used a load resistor and a trick I read about the
other night.  Placing the resistor 1/4 wave from the end far end
gives a virtual ground.  At 6 meters, that's just 9 extra feet
of wire and much easier to implement than a ground....

My testing with EZNEC showed that it does exactly what they say
it does.  It eliminates the by-directional pattern but leaves
the main lobe in the forward direction unchaged.  The real
advantage is that it eliminates any standing waves making it
easy to design a matching network.
http://www.ew.usna.edu/~bruninga/meteors.html

> (old military field radio trick in 
> the 30-76 MHz PRC-25 and VRC-12 band.
> Works well, I (and many others) taught it 
> in the Army, personally used it  less than 
> 2 years ago in a "distant land".  Still works! 
> and meant the difference between zero comm and 
> 5X5.  Simple idea, seldom used, ALWAYS works 
> better than a whip, AND works better than a 
> 5 element beam at 35 feet.  Surprised me too 
> when we did a controlled side by side test beam 
> with a 1-1 VSWR and the vertical half-rhombic at 

Yes, and at 2 meters, it is less than 40 feet long...

> b. .  -----  
> Original Message ----- 
> From: "Robert Bruninga" <bruninga at usna.edu>
> To: "'tacos AMRAD'" <tacos at amrad.org>; "'TAPR APRS Mailing
List'" 
> <aprssig at lists.tapr.org>
> Cc: <bruninga at usna.edu>; "'Michael Chisena'"
<ka2zev at yahoo.com>
> Sent: Wednesday, January 02, 2008 2:09 PM
> Subject: 6m meteor Scatter project (radios&ants)
> 
> 
> > Mike,
> >
> > I have updated my Meteor Scatter web page:
> > http://www.ew.usna.edu/~bruninga/meteors.html
> >
> > To focus entirely on setting up a USA Meteor Scatter Email
> > delivery system for emergency comms.  We simply add RX's to
each
> > APRS Igate, and the rest of the infrastructure exists.
Done.
> >
> > The new tidbit I came up with is how to cheaply get GAIN
> > antennas for these receivers.  And the answer is simply a
100
> > foot long wire. . Just 100 feet gives over 12 dBi of gain in
a
> > fixed direction.  Just perfect for 6m MS!
> >
> > So get that pallet of radios.  I'll kick in $$$ to make sure
we
> > can get a whole lot of radios...
> >
> > Bob, WB4APR
> >
> >> -----Original Message-----
> >> From: tacos-bounces+bruninga=nadn.navy.mil at amrad.org
> >> [mailto:tacos-bounces+bruninga=nadn.navy.mil at amrad.org] On
> >> Behalf Of Bob Bruninga
> >> Sent: Saturday, December 29, 2007 3:03 PM
> >> To: Paul Rinaldo; tacos AMRAD
> >> Subject: 6m meteor Scatter project.
> >>
> >> The #1 advantage of this current 6m MS proposal is that it
> >> does not attempt 2-way exchange.  It takes unique advantage
> >> of these primary issues:
> >>
> >> 1) APRS Email Mission is delivery of SINGLE Email packets.
> >>
> >> 2) A single successful packet results in real-world value,
> >> sender-to ANY human recepient on the planet
> >>
> >> 3) Space-diversity: Receivers at IGates all over the
country
> >> all linked in real time via the internet.  THis improves
> >> reliability by an order of magnitude.  Not just one area of
> >> the sky, between point A and B, but ALL areas of the sky
> >> beteeen A and B-thru-ZZ are potential meteor reflectors.
> >>
> >> 4) Only one packet to one receiver is needed for 100%
success.
> >>
> >> 5) Individual testing is one-handed.  All IGate receivers
are
> >> automomous and listening 24/7.  SO any tester only needs to
> >> TRANSMIT his email, and then watch his PC for success.
> >>
> >> It is this unique "emergeny outgoing email" mission,
> >> unique-existing APRS infrastrcutre and existing email
engines
> >> that make this new project quite viable and not necessarily
> >> dependent on a critical mass.
> >>
> >> Lets get some on the air listening...
> >>
> >> Bob, Wb4APR
> >> _______________________________________________
> >> Tacos mailing list
> >> Tacos at amrad.org
> >> http://www.amrad.org/mailman/listinfo/tacos
> >>
> >
> > _______________________________________________
> > Tacos mailing list
> > Tacos at amrad.org
> > http://www.amrad.org/mailman/listinfo/tacos
> >
> >
> > -- 
> > No virus found in this incoming message.
> > Checked by AVG Free Edition.
> > Version: 7.5.516 / Virus Database: 269.17.13/1207 - Release 
> Date: 1/2/2008 
> > 11:29 AM
> >
> > 
> 
> 





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