The first sub section is Tripods, Extensions and Probe Mounts. The full catalogue or Web site will inform you of the size and various interconnect threads. We have tried to provide an interface to nearly all the known EMC antenna manufacturers. For any given antenna first decide at what height you will require the device to be mounted relative to the surface over which the measurements are to be made. It is most likely the antenna will have to rotate through 90 degrees to satisfy the polarisation requirement.