[amsat-bb] Re: Phase 3

i8cvs domenico.i8cvs at tin.it
Sun Sep 22 03:26:57 PDT 2013

```----- Original Message -----
From: "Daniel Schultz" <n8fgv at usa.net>
To: <amsat-bb at amsat.org>
Sent: Sunday, September 22, 2013 5:26 AM
Subject: [amsat-bb] Re: Phase 3

> >> Could a 3U cubesat with deployable solar panels power a 1 watt,
> >> 100 kHz, mode U/V transponder?
>
> Yes, I believe that is possible, with deployable arrays we might even be
> able to do ten watts, but such a tiny satellite in such a high orbit will
> require big antennas on the ground just to hear it. I can already hear the
> cries on amsat-bb about the "elitists" who want to push the little guys
> out of the satellite game so they can keep the HEO satellite all to
> themselves.
>
> Dan Schultz N8FGV
>
Hi Dan, N8FGV

You are correct because remember OSCAR-13 carried on a U/V
transponder with 50 watt pep and a 2 meters RHCP antenna with
10 dBi gain.

Now if a 3U cubesat  with deployable solar panels has a U/V transponder
with 1 watt power the difference in EIRP between OSCAR-13 and the
above 3U cubesat only considering power is:
10 log   (50/1 ) = 17 dB
10
Now consider that the average of OSCAR-13 ground station were using
2 meters crossed dipole antennas with 13 dBi gain and you will see that
to receive the downlink of the above 3U cubesat with the same S/N ratio
of OSCAR-13 you must use a 2 meter crossed dipole antenna with
13+17 = 30 dBi gain i.e. an EME antenna.

Now consider  that is possible, with deployable arrays we might even
be able to get ten watt from the 3U cubesat than the difference in EIRP
between OSCAR-13 and the  above 3U cubesat only considering power is:
10 log    (50/10 ) = 7 dB and you will see that to receive the downlink
10

of the above 3U cubesat with the same S/N ratio of OSCAR-13 you
must use a 2 meter antenna with 13+7 = 20 dBi gain i.e. an array of
four antennas with gain of 13 dBi each wich is convenient only for
those amateurs working EME

I don't know what could be the 2 meters antenna gain on board of a
3U cubesat but I believe not more than the gain of a crossed dipole i.e.
2.14 dBi wich do not change significantly the above budged situation
in order to reduce the gain of the 2 meters ground station antennas.

We will talk about on the phone as soon you will be in Naples in the
next few days from 28 September to 1 October

73" de i8CVS Domenico

```