A fun vertical antenna can be made by cutting a horizontal slot in a satellite dish, as documented in e.g. http://www.w6nbc.com/articles/2016-3QSTdishslot.pdf and discussed in How does a slot antenna work? and other questions here. But how would this modification affect the original (satellite receiver) antenna system?
Of course, trying to use both antennas simultaneously would run into practical concerns — aiming of the dish necessary for satellite reception vs. what would be ideal for a station's desired 2m pattern, whether the LBNF and/or satellite receiver would appreciate being party to a 25W ham signal, etc. But all the same, I'm curious if/how the slot affects the parabolic reflector itself.
I know that a reflector needn't be completely solid, and can work with a metal mesh or even a wider grid/skeleton of wires. So is a narrow slot — surprisingly effective at its own VHF frequency — also totally insignificant at the EHF frequencies? Or does a long continuous hole affect the aperture efficiency more than losing equal surface area via small disconnected holes would affect it?