[amsat-bb] Re: A0 40 replacement - mode K cubesat?
ross at topwire.co.nz
Thu Sep 5 00:09:02 PDT 2013
How feasible is it to fly a mode K (15m uplink, 10m downlink) linear
transponder on a cubesat?
I expect that retty much any ham with an HF transceiver would be able to
work this bird, and I expect that due to the lower frequency, the
footprint might be a bit larger than that of VHF/UHF bird in the same
orbit and doppler shift would only be about 7% of that experienced on 70cm.
The biggest problem that I see though is squeezing a somewhat efficient
10m antenna into a cubesat and deploying it by remote control once on
orbit. (I think that the cubesat antenna should be optimised for TX
performance, as cubesat TX EIRP capability is severely limited compared
to the average HF transceiver).
Would two 2.5m lengths of steel tape (the same stuff that tape measures
are made out of) - mounted on opposing sides of the cubesat, be able to
unroll in microgravity to form a generally straight 1/2 wave dipole with
a low risk of tangling, snagging or kinking, etc?
Alternately, what about using some sort of thin plastic tubing
(something like dialysis tubing, but suited to the space environment?)
with a wire inside it, and rolled up. Then, once on orbit, the tubing is
inflated with self-expanding polyurethane foam, which will extend the
tube (and the wire inside it). The foam will then harden, so future loss
of gas pressure in the plastic tube (micrometeorites?) will not cause
failure of the antenna?
73 ZL2WRW Ross Whenmouth
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