Open-circuit microstrip termination/match to air line

I need to check EM properties of my antenna feed network, so to save time, I want to replace patches with equivalent open-circuit "loads", each with input impedance of 50Ω. How would I go about it? I can use stub matching to design a termination given the load, but how do I do that if my load impedance is infinity?

I know it can be done since the patch is effectively matched to open circuit, but how do I do it with microstrip lines?

1/2 wavelength unterminated? is this what you want? why?

Normally antenna are tested with return loss.

Something doesn't sound correct about this...