[Lowfer] how strong would half wave dipole be?

[Andy Bell]

--- Art <KY1K at verizon.net> wrote:
> I recently became interested in ballooning, and
> began to wonder about launching a 1 watt transmitter
> with a half wave dipole antenna. 
> With small diameter wire (for light weight), how far
> could I be heard on 185 KHz if the antenna was     
> oriented vertically, and flying between 
> 20K and 100 K feet above sea level?

  Hey Art: Part 15 rules state that maximum radiator
length including feedline, and ground if used may not
exceed 15 meters ( approximately 50 feet ) in length.
A half wave at 185KHz would be around 2600 feet long,
a bit tooooo long for part 15 compliance.

 
> Would the QRS signal be readable in the entire USA,
> or would the range be much lower?

  That's probably a hard question to answer since it's
most likely not been done before. But in my opinion,
the higher you go you will at some height above ground
reach the law of diminishing return where going any
higher will not help and may even hurt your efforts.
For instance going higher than about 3000 feet ( half
wave above ground ), the ground losses would become a
non-issue however I would also assume that the closer
to the " D " layer you get the sooner it would absorb
your signal, assuming daytime operation. For night
time operation; ( an un-educated guess would be )
since the " F " layer is about 150 miles above the
earth, the 19 mile height ( 100K feet ) would have
negligible effect, or: could possibly reflect your
signal back down sooner and closer in, shortening the
distance covered. I certainly can't substantiate any
of this, it's only my opinion. That and $ 1.25 will
get you a decent cup of java. 73, and happy balloning:
Andy - KU4XR




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