[amsat-bb] EsHail Microwave transponder satellite
pa3fym at amsat.org
Tue May 31 10:07:22 UTC 2016
>What are other folks planning to use on the uplink 2400 MHz and the down
>link at 10,489 MHz, for the narrowband linear transponder ?
I will use a cheap injection locked X-band PLL LNB with dielectric rod
and additional converter to let the NB transponder land inside one of the
bands my transceivers accomodate.
For the S-band uplink a dedicated (simple!) TX converter is now prototyped.
Output of the converter will be around 5 dBm to be inserted in an old UMTS
(2.1 GHz) module, capable of delivering around 20 - 30W at 2400 MHz on the
bench with this drive. Of course uplink output can be tweaked.
I am also busy with the dual band feed, of which the downlink of course is inside the LNB.
For the uplink I made a 6 turn LHCP helix but am now fiddling with the matching due to
mechanical boundary conditions. At this moment of writing I (still) haven't a good match
but I reckon this mechanical issue will be solved soon.
Secondly I need to experiment with the phase centers of both up- and downlink
to maximise overall efficiency. Even when I'm not able to equalise both phase centers
I have some room in my uplink budget to compensate for suboptimal illumination.
In my prototype the LNB looks 'through' the helix.
Antenna will be a Triax 88cm broadcast satellite dish with f/D of around 0.6.
All internal frequencies will be/are locked to GPS which allows my idea of building a
SUT (satellite user terminal) [for portable use] in conjunction with one (1) transceiver.
In other words, my concept will be that Es'hail2 behaves like a normal
amateur band, albeit with some delay ;-)
More information about the AMSAT-BB