You do have the model of the Sigma built the way I suggested and it is working in EZNEC with a phase delay that is much too long to work in the field. The point here was to prove that EZNEC needs to see a 1/2 wave phase shift and that can only be the case if it misses just about all of the cones phase corrected radiation.
The collinear model I suggested was built only to clearly demonstrate this fact by using a phase shift design whose electrical length and total unfolded physical length would be virtually the same. The shorted stub phase delay does radiate on this antenna and distorts the radiation pattern badly.
This makes that collinear Sigma model unsuitable for comparison to other collinear models not suffering from a phasing network that is radiating and causing heavy distortion in the pattern. They should also be compared in free space to eliminate ground gain variables and distortion in the pattern from those ground reflections.
The idea here was to find a way to test what EZNEC was telling me about how much of the antenna it thinks was radiating, its phase and relative magnitude. Adding a known 1/2 wave radiator on top and adjusting the phase delay in the field for maximum gain in the distance is an ideal real world test for this.
The radiation current and phase distribution across an end fed 1/2 wave is a given we can take as common knowledge. Adding it to the top of another antenna in question and peaking the gain in the phase shift will identify the relative magnitude and phase of the entire radiator below this phase delay.
If the Sigma cone was just transmission line or had low amounts of in phase currents radiating from it, that means it's just a fancy looking 1/2 wave J-pole. It also means the phase to drive the second collinear 1/2 wave must be completely inverted the full 180 degrees. Just like EZNEC suggests.
Since the gain peaks with an electrical 1/4 wavelength or 90 degree total phase shift, that proves the cone is producing fairly strong radiation currents that effectively combine with the upper element in the far field. When I consider this along with the CST data, I have conclusive proof the Sigma is a "non apparent collinear". Needless to say all the EZNEC models we have seen on the Sigma have been nothing less than misleading too.
