EIRP vs Dish size (Stagnant or Decreasing) ?

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EIRP vs Dish size intro articles :
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SatLex® - EIRP Reception - Satellite Calculators

Calculate the receive signal strength and link budget from a satellite's EIRP value. Find out how large a dish you need for reliable reception at your location and operating frequency.
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I read here that in early 90s, 5m to 3.7m dish size were required to lock C band signal in official footprint coverage region whereas now it is reduced to 1.8m.

1. I am interested to know what was the size of dish required to view ku band transmission in 90s (or probably earlier than this decade !).
2. Is transponder power increment reached its saturation point and no more possibility for increasing it without sending heavy solar panels with satellites during its launch time as it seems antenna efficiency enhancing technology quite slow ? What is latest technological update regarding this (any future reduction in dish size possible !!) ?
 
Very interesting question.
I think we must not focus on dish size or footprint, because good or bad reception of a specific signal depends from many points, but in particular from SNR value (signal to noise ratio in the reception site).
This value has very different impact receiving analog or digital signals, and between digital signal types, too.
I had my first dish in 1989. During that period (good old analog era), I remember that SNR values of around 6 dB was enough for a good home reception, but for broadcasting or professional reception a value of 9 dB was required.
To get first generation Eutelsat satellites or Intelsat V or VI satellites, you colud obtain such values with around 1.8m and 3m dishes respectively but, as I know, many broadcasters used 3.7m or more.
Keep in mind that LNBs noise figure was no less than 1.5 dB in those years.
Then LNBs NF dropped was dramatically, but going digital the situation became worser.
Now minimum SNR value to lock a specific signal depends by new and more complex parameters like FEC, modulation type and so on.
For example, a DVB-S2 8PSK 3/4 transmission need no less than 8 dB for locking, but broadcasters require 12dB.
So, with the same satellite power, if in analog era you could get a signal using, say, a 2m dish, now a bigger one could be needed.
In other hands, signal owner can restrict the chance that its signal can be locked just modifying modulation parameters. There are modulation types requiring no less than 13 dB to be locked!
Now regarding satellite transmission power.
In the same old era (end 80s, beginning 90s) typical power was around 48-49 dBW. First Eutelsat and Intelsat satellites were a litle bit lower (particularly feeds, around 45-46 dBW), Astra 1 was a little bit stronger (around 52 dBW). Not sure about the actual power of main European commercial satellite like Hotbird, probably around 54-55 dBW, please correct me if I wrong.
I believe that strongest satellites in the history were TVSat and TDF, located at 19 West at the end of the 80s.
Those satellites were designed in the 70s when noise figure of every Ku band LNBs was no less than 4 dB, and when they was launched and deployed (after big big delays) they was just old and was trashed after few years.
I hope this helps.
 
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