I think the fact that some radio energy might be diffracted due water drop on the dish or feeder is in no relation toward the attenuation due distance and especially if this distance has to be bridge through millions of rain drop where the dish and feeder will only have some... And shielding is not needed for the high frequencies since 60Ghz virtually has no sidelobs you want to suppress.You are wrong as many say so,..
if there is no water on the dish and radiator [feeder] means a much more stable link, because we have a very focused beam.
The same is how you set up a shield for powerbeam, it works much better and more stable than without a shield/radom...
In 5Ghz even with a shield signal 'leaks' to the sides. Put another 5Ghz radio 10 meters away and aside of the best dish plus shield in the market and you still pickup considerable signal.
Do the same with a 60Ghz radio and you don't even see any signal anymore.
I have 4 wAP60G AP's in a mast all facing in their 90 degree sector only 1 meter apart and they already hardly can see each other. Only long run (minutes) scans see some signals in the range of 20 or less and dissapears.
I can't even connect a client unit at 20 meters away to get it to connect to an AP that he looks from aside.
Any 5Ghz CPE antenna I can connect at even 50 meters away from a RF-Elements cone (these are supposed to be top of the bill antennas with near 100% side lob suppression).
Shielding or covering 60Ghzs in my humble opinion gives very marginal effects. Probably not even measurable. The attenuation is the killer here and no matter how big the dish is, you can only focus that much signal, and you can only catch signals that reaches you.
A slightly bigger dish as the standard 33cm LHG might do something but it needs a special LNB further away from the focal point otherwise the other part of the dish is not doing anything for sending. Only for receiving.
So your picture of the LHG lnb just mount on a bigger dish doesn't do nothing.
If you think otherwise do some real tests with similar conditions etc. and show us.