With a good coupler that has high directivity and decent match it's super easy to do.
If indeed it is super easy as suggested, I would like to see the experiment ran.
OP didn't provide a lot of background on package types they were interested in investigating.
... mismatch caused by component footprints on PCB microstrip layouts, up to 3 GHz.
I assume you would start with some sort of custom controlled impedance test board with your various patterns. You need to somehow isolate the effects of the footprint. Run the entire test on a single PCB? OP may be able to provide some insight as to what footprints looked like. Maybe try and use all 50ohm parts. It seems like you may be able to get some sort of relative measurement at best.
It seems like a job for the simulator but if it really is supper easy, please set it up.
Thanks.
To be honest, I already did some simulations and the results even looked real (
)! But there are many ways to fool oneself in a simulation. For example, in one of my simulations (I don't remember the data now, but if I recall correctly), a capacitor footprint's S11dB crosses the 20 dB mark at 1 GHz or so. But with a ground plane cut-out, S11dB is still below 20 dB at 3 GHz. But this simulation is done using lumped capacitance, not real capacitance, with perfectly matched lumped ports, lossless metal, with possibly additional misconfiguration. So it's dubious at best.
So my original motivation is to get a reality check - can I trust my simulation setup? I want to start at something really basic, something like...
1. A 50-ohm microstrip with two SMA connectors, far-end terminated by 50-ohm coax load. One board has solid ground plane and another has cut out under the center conductor for impedance compensation.
2. A 0603 AC coupling capacitor footprint between a 50-ohm microstrip, far-end terminated by a 50-ohm coax load, One has solid ground plane and another has cut out.
Compare experiments and simulation results for different cut off sizes. If I can even detect a difference at all, I'll call it a success.
But after reading your criticisms, I think it might not be a good idea. The measurements I was trying to do will possibly be drowned into the noise floor. Looks like my goal is too ambitious, perhaps I should start from some easier experiments that are easier to measure, such as a microstrip couplers, filters, etc, 800 MHz.