[amsat-bb] Re: A0 40 replacement - mode K cubesat?

David Johnson dave at g4dpz.me.uk
Thu Sep 5 01:15:39 PDT 2013


ZACUBE is a HF beacon. Something like this may be a foundation for what 
you're suggesting.


It's riding along with FUNcube in the same POD. Take a look at this 
page, about half way down you'll see the ZACUBE deployment mechanism.




On 05/09/13 08:09, Ross Whenmouth wrote:
> Hi,
> 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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