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Old July 18th 04, 07:16 PM
John Doty
 
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Frank Dresser wrote:

I recognized Telemon's antenna formula as something very much like the
transmission line formula. I'm not sure how it applies to resonant
receiving/transmitting end fed wires. If it does, I'd like to learn
something.


For a wire antenna, the field configuration near the wire is very
similar to the field inside a coaxial cable. Unsurprisingly, it has
similar behavior: the bulk of the energy tends to propagate along the
wire and not radiate. This leads to Schelkunoff's approximation: you
calculate the current distribution along the antenna as if it was a
transmission line, and then calculate the radiation due to that current
distribution. You can get the antenna impedance by calculating the
impedance of a lossy transmission line (with loss equal to the
radiation) with the assumed current distribution. You get the reception
properties by reciprocity.

Not only that, but the rocket scientists stay stuck on the ground!


Good thing. Even when the rocket fails and destroys your payload, you
get to go home and hug your wife and kids. It's happened to me twice so
far (HETE-1 on a Pegasus in 1996, and ASTRO-E1 on a M-V in 2000).

-jpd


 
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