[amsat-bb] HF satellite Antenna

["Robert Bruninga" <bruninga@xxxxxxxx>]

Antenna designers note:

Our next amateur satellite will be a 5" cubesat but it needs
a piano wire HF antenna for 29 MHz.  A dipole is impossible with
our planned deployment design due to risk of entanglement.

Thus a monopole.  But with only the counterpoise of the
5" cube, a 1/4 wave monopole wont work.  We are thinking
of a full size ½ wave radiator end-fed.  The antenna will be
a .02" dia length of rigid nitinol wire.  If someone wants to
volunteer a matching circuit and optimum length, we'd be
 happy for your input.

We also would want the broadest, most forgiving tuning,
since its hard to assure a perfect tune when you cant
get inside nor have any external wires (going to an SWR
bridge) for which to use in tuning...  In otherwords, is
there something shorter than ½ wave that will tune up 
nicely?

Excessive length cuts the satellite lifetime.  WIthout any
antenna, this satellite will only last 2 years max.  Even the
17 foot .02" piano wire will cut the life (due to drag) by as much
as a year...

Don't even think about tapemeasures.  They would cut the life
to months...

Bob



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