Re: [amsat-bb] re: Lunar repeater?

["Mike Hooles" <Mikehooles@xxxxxxxxxxxxxx>]

thanks William,
it's your calculations that had me thinking that it would be possible to
come up with a small FM or better still SSB/CW solar powered repeater
weighing  a kilo or less.
I noted some time ago a solar panel being tested on the shuttle that was
paper thin and folded down to a very small size, so combining that with the
paper antennas here was potentially a very lightweight unit.
Regards
Mike G3LGR
----- Original Message -----
From: "William Leijenaar" <pe1rah@hotmail.com>
To: <amsat-bb@AMSAT.Org>
Sent: Saturday, April 26, 2003 5:45 PM
Subject: [amsat-bb] re: Lunar repeater?


> Hi AMSATs,
>
> I'm happy that the lunar repeater topic is started again :-)
> But I see that most of the amateurs still don't understand that a moon
> station is not that difficult to work !!!!! A moon transponder IS NOT LIKE
> EME !!!!!!
>
> EME uses the moon surface to REFLECT your own power, and has lot of
losses.
> A transponder has not these losses !!!
>
> Then amateurs are talking about tracking antennas, extreem warm/cold,
> batteries that will die etc etc... these are only DETAILS.
>
> My answers to this:
> -------------------
> Tracking antenna's
> ==> In my opinion, not specially needed. Just fixed antenna is okay. This
> will be the same problem like AO40 with its Squint problem.
>
> extreem warm/cold
> ==> There are many technical solutions for it. E.g sun shield, like
> sun-glasses that only pass through little sun-light.
> ==> I just read that there are some placed on the moon with average
constant
> temp. of -64C. Thats also a solution, and a station can technically be
made
> to work in this enviorment.
>
> Batteries:
> ==> When they can not survive we only use solar-cells. Yes, the station
will
> only work during sun-light, but Ao-7 is also working only in sun-light but
> nobody complains !!!
>
>
> Then about the difficulty to work a station on the moon. I showed in a
> message before that it is not that difficult as many hams think. Many hams
> think it is like EME, but its not. A MOON STATION IS NOT LIKE AN EME
> CONTACT.
>
> I will re-write the calculations I have showed before:
> ------------------------------------------------------
> Communication with a station on the moon can be done with common HAM
> equipment, like shown below:
>
> On 70cm when both stations use 20W power and 13dB antennas:
> ---------------------------------------------------------
>           Uplink 20W       =  +43dBm
>           Uplink ant. gain =  +13db (medium yagi)
>                 -------------------
>           Uplink ERP       =  +56dBm
>           path losses      = -197dB
>                ---------------------
>           ERP on the moon  =  -141dB
>           Ant gain moon    =  +13dB (medium yagi)
>                ---------------------
>        Moon reciever input = -128dBm
>
> On 10GHz when both station use 10W power and 80cm dish ant. (36dB):
> -------------------------------------------------------------------
>           Uplink 1W        =  +40dBm
>           Uplink 80cm dish =  +36dB
>                -----------------------
>           Uplink ERP       =  +76dBm
>           path losses      = -225dB
>                -----------------------
>           ERP on the moon  = -149dBm
>           80cm dish moon   =  +36dB
>                -----------------------
>        Moon reciever input = -113dBm
>
> These stations are not like EME station :-)
>
> PS: Some amateurs are serious interresting in making some lunar
transponder
> station ???? (not complaining but just showing that it can be done :-)
>
> 73 de PE1RAH, William
> ---
>
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> ----
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----
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