Hi:
Yes. Probe-feed is a good way. To build one or multiple probe feeds on IE3D, you just enter a series of vertices as if you are entering a polygon on the patch level. Then, you select ENTITY->PROBE FEED TO PATCH. You enter the radius value and change the default settings for other values. Select OK and IE3D/MGRID will build the probes for you. You can also parameterize the probe locations for EM tuning and optimizatoins. It is inconvenient to parameterize the probe radius on IE3D/MGRID. However, you can use IE3DLIBRARY for fully parameterized models. On IE3DLIBRARY, you can define a patch. Then, you can define a probe feed in INSERT->3D OBJECTS->CYLINDRICAL PROBE PORT. You can define the probe radius, the z-coordinates (or length) as equations of tuning variables.
Best regards,