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[aprssig] 6m Meteor Scatter longwire matching

Robert Bruninga bruninga at usna.edu
Thu Jan 10 19:54:57 UTC 2008


Two pieces of 70 Ohm cable make a perfect 1/4 wave transformer
from 50 ohms up to the 400 ohms of the long wire 6m Meter
Scatter antenna.  Just got it up today.  See the details on the
APRS Meteor Scatter web page: 

http://www.ew.usna.edu/~bruninga/meteors.html

In another day or so, Ill have 1200 baud APRS Meteor Scatter
going.
Bob, WB4APR

> -----Original Message-----
> Subject: [aprssig] RE: 6m meteor Scatter project (radios&ants)
> 
> > Or of course you could dig in a ground and 
> > terminate in a 150-300 ohm resistor at the 
> > far end.. 
> 
> My design uses a load resistor 1/4 wave 
> from the end far end which gives a virtual 
> ground.  At 6 meters, that's just 4.5 extra 
> feet of wire and easier to implement...
> 
> EZNEC showed that it works.  It eliminates 
> the by-directional pattern but leaves
> the main lobe in the forward direction 
> unchanged.  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 
> 





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