Reference plane for waveguide port

I'm simulating some microstip patch antennas. One of them is a simple patch with inset to match the feeder.

Any idea about till where the reference plane of port should be ? till the edge of patch, or till the the point of meeting between feeder and patch?

you needn't define the reference plane here, in case of P A T C H antennas all you need is the magnitude of s11 not its phase.

I agree with adel_48 as long as your feeding line is 50 ohm of characteristic impedance. However, I would put the reference a little further than the p.a.t.c.h edege to avoid effects of coupling with the inset and so on.
regards

In fact, I have learned from CST examples. You can check them as well. It is preferably to do that for the reason you mentioned about the phase.
It is so clear for the antenna without inset. With inset, I put also little bit far from the inset edge. I wanted to know if there is some functions can define the phase that will happen doing that.

I have a similar question in modeling my circular patch antenna. If I want to determine the behaviour of the structure composed of the circular patch and the microstrip line inset feed, do I have to specify a distance to the refrence plane or not?