[amsat-bb] new sats and 23cm

Thu Aug 6 00:54:33 UTC 2015

FUNcube on ESEO says 100w EIRP for their L/V FM transponder. I don't
recall seeing any estimates for Fox-1C or Fox-1D.

http://amsat-uk.org/2013/02/02/amsat-uk-to-provide-amateur-radio-payload-for-eseo-satellite/

I did link budget calculations a while ago (can't find them though...)
and came to the same conclusion, assuming the sensitivity of the L
band downconverter on Fox-1C and 1D is similar to the specification
for the 435 MHz receiver (-120 dBm for a 12 dB SINAD), about 100w EIRP
will be needed at maximum range given the high path losses on 23cm.

73,

Paul, N8HM

On Wed, Aug 5, 2015 at 8:46 PM, Greg Dolkas <ko6th.greg at gmail.com> wrote:
> I also have 10w on 23cm from my Yaesu FT-736R, and a reasonable beam on the rotor.  At least, it worked quite well through the recent LEOs.
>
> How much EIRP are we expected to need for tthis one?
>
> Greg KO6TH
>
>
> On August 5, 2015 5:52:06 AM PDT, David <dwarnberg at verizon.net> wrote:
>>Zach, all... thanks very much for all the replies, it does give me some
>>things to ponder...  I do realize the add on 23cm module for the
>>IC-9100 has only 10 watts output.. so it seems to limit my options or
>>add more cost to the final setup...
>>
>>Again thanks everyone for the replies, as par for the course you guys
>>are very helpful
>>
>>Thanks All
>>
>>David,  KK4QOE
>>
>>-----Original Message-----
>>From: Zach Leffke [mailto:zleffke at vt.edu]
>>Sent: Wednesday, August 05, 2015 1:20 AM
>>To: David
>>Cc: amsat-bb at amsat.org
>>Subject: Re: [amsat-bb] new sats and 23cm
>>
>>Sorry, typo... G/T doesn't make sense since uplink only band....please
>>substitute 'affect G/T' with 'affect overall link budgets' in my
>>previous email.
>>
>>Apologies, its late and I need sleep.
>>
>>-Zach, KJ4QLP
>>
>>On Aug 5, 2015 1:12 AM, Zach Leffke <zleffke at vt.edu> wrote:
>>>
>>> Directive Systems and engineering has loop yagis specifically for the
>>amateur satellite service in this band.  It is what we will be using in
>>the Virginia Tech ground station.   No feedback yet on performance
>>(we're not up yet) but they look very well made and the folks at the
>>company are fantastic and they have a great reputation with their
>>antennas at microwave and up.  They are fairly compact and lightweight
>>as well and could likely be added to a G5500 style setup with ease and
>>minimal additional strain on the motors.
>>>
>>> I'm not aware of any omnis for this band off the top of my head, but
>>being that it is an uplink only allocation, lack of gain and increased
>>path loss could be made up for with power (bearing in mind the recent
>>threads on proper uplink power levels).  Consider though that there is
>>about 18.8dB and 9.7dB of additional path loss over VHF and UHF
>>respectively.   Assuming similar rx gains and noise performance on the
>>bird at 23cm, as well as atmo/iono losses, that additional loss will
>>have to be overcome on the ground, either with increased antenna gains,
>>or with increased power. Given that the 9100 makes about 10W on 23cm,
>>it may be time for a decision.  a) 23cm module plus fairly beefy amp
>>plus homebrew omni, or b) 23cm module plus rotator system plus well
>>built (and factory tuned) yagi.
>>>
>>> Personally, I'd recommend option b with rotator plus beam plus lower
>>power, mainly because antenna gain is easy/cheap at 23cm and PAs can be
>>expensive/tricky at 23cm,  but I have access to existing rotator
>>systems which bias my opinions.
>>>
>>> My two cents....
>>>
>>> Also it might be interesting to see some more rigorous analysis and
>>antenna designs for 23cm (omnis and beams).  Maybe comparisons of
>>various omnis and various beams and how they affect G/T (imagine a cute
>>little lindenblad or turnstyle or eggbeater for 23cm and how physically
>>small it would be compared to what we are used to at VHF/UHF, it would
>>be roughly a third of the size of its UHF equivalent!). Once we can get
>>some details from the Fox engineering crew or Ops crew on the expected
>>performance of the uplink receiver on 23cm, could make for a good
>>article or two for the Journal (especially the bit on 'microwave omnis'
>>and their feasibility, I'm sure the eng/ops crew has or will have a
>>solid handle on the overall receiver performance and link budgets).
>>>
>>> -Zach, KJ4QLP
>>>
>>> On Aug 4, 2015 11:32 AM, David <dwarnberg at verizon.net> wrote:
>>> >
>>> > I see lots of talk about some new sats going up that will be
>>utilizing 23cm.
>>> > so I have some questions..  first let me explain what I have setup
>>> > currently.
>>> >
>>> > 1)      Icom IC-9100 (23cm module not added yet)
>>> >
>>> > 2)      M2 eggbeaters (70cm and 2m) with preamps
>>> >
>>> >
>>> >
>>> > So I am contemplating adding the 23cm add on for the 9100 but
>>> > perplexed about an antenna. suggestions?
>>> >
>>> >
>>> >
>>> > Thanks
>>> >
>>> >
>>> >
>>> > David, KK4QOE
>>> >
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> --
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