RX antenna gain on the QO-100 / pathloss

You can calculate/estimate the 'receiving gain' of the QO-100 antenna assuming that the satellite is on 38500 km above the Earth and needs to illuminate the whole Earth with minimal 'spill over'. Assume (I don't know exactly) that you've -3 dB points at the edges of the Earth, then you can calculate the (-3 dB) opening angle and from that you can calculate the 'gain'.

But there is a calculation concerning the uplink budget in the formal/original Es'hailSat presentation for the ITU (some years ago).

we would need some "reference".

We can measure the dBm value at the LNB's output, but what is the conversion gain of the LNB ?

It will be different for various brands ?

Has somebody already measured this conversion gain ?

See below the sheet I referred to (sensitivity (SFD) of the tpx is given) and also read this document

How I read that sheet: these are worst case numbers (second bullit).

In the sheet the word 'Europe' is not mentioned, at least I do not see it.

'Coverage peak' <-- say cantral part of the footprint
'EOC' <-- end of coverage (say 5 - 10 degrees elevation)
'Elsewhere' <-- well ... elsewhere ; -)

One thing not to forget: Plenty of WX conditions can effect your overall loss. For example, in the early morning if the sun is on my dish, I can see the noise floor higher than at late at night.

Then we have cloud cover. At both 'ends' of the "QSO" (or Beacon Uplink site, or GHY Downlink). Let alone rain drops on the dish, at either ends! Here in the UK they are threatening hail today, so that might well be an interesting effect!

Which brings up something else I've been thinking about over the last few weeks...Would weather reports from key sites (Bochum, QARS, Es'hail Satellite Control Centre, GHY etc) on the Upper Beacon be useful ?

I know there's times I've gone "Where did 6dB go ?! I had 14dB SNR last night, what's changed in 7 hours!", so gone fiddling with the feed position to no avail, and *then* find out its windy and raining in Bochum, or looked up at the sky here! Ditto with Goonhilly.

(If you are comparing your system to the Beacons, and/or GHY's SDR, then you need to make sure you are aware of local conditions at each site)

If there's interest in discussing WX and other environmental effects, we can start a new thread (I really just wanted to point out that the WX can effect these measurements on this thread, having been caught out myself)

73s

Iain

(and as if by magic, 5 minutes after I post this, the great attenuator from the sky comes down in liquid form...British Weather, have to love it!)

I have no insight information, so the following is an (educated?) guess: Looking e.g. at BADR4's Ku-band footprint (which is not a global beam!) you see that in the centre it's 50 - 51 dBw and at the edges 6 dB (or more) less, which translates to dish sizes in order to receive the TV programs.

The transmit Esh2 Ku EC-horn has 17 dBi (see specifications), so this translates to a certain -x dB (x being the design specifications) beam width from which the relative loss / output power can be derived. Because the beam is global I think around 6 dB may be added .. which translates to half dish size.

Cf the sheet: 89cm dish at EOC vs 50 cm dish in Coverage peak = 'around' 6 dB (5 dB to be precise).

Of course the values in the sheet are the design goals, so I am not aware which values are realised ... I did not sign any NDA concerning Es'hail-2 ; -)

Rain attenuation in dB/km can be seen below. From the graph it is clear that 2.4 GHz is not much affected by rain. (except when water gets into the feed itself and ruins the matching).

For 10 GHz it can be a problem, but then it has to pour down. There are lot of information on Sat-TV and rain attenuation on the internet. One report stating that: "For Western Europe rain attenuation only excees a couple of dB in 0.1% of time".

73 Ole

You need to consider the slant path attenuation - there is a very good ITU-R P series recommendation on this. P.618. https://www.itu.int/dms_pubrec…18-12-201507-S!!PDF-E.pdf