[BC] RF fields around base of shunt fed monopole

[John Lyles]

I have some questions for the collective:
Looking at FCC OET-65 guidelines for RF exposure around 1 kW AM broadcast monopoles, it looks like the MININEC models suggest 1-3 meters separation from the base for a 1/10 to 1/4 wave tall structure at 1.5 MHz. This is the point where you would not exceed the magnetic and electric field allowable limits for controlled areas with knowledgeable workers. Has anyone actually verified these calculations around their tower base?

Also, I imagine the model was a series fed, base driven monopole. What if shunt feed with a wire skirt - a folded unipole? Can i expect similar levels of RF around the circular wire that ties the vertical skirt wires together at the bottom, over to the ATU? In some cases, the ATU might consist of just a series capacitor to cancel the inductive part of the input Z. I would think that, depending on the complex impedance at the feed point of the tower, the fields could vary quite a bit, depending on the reactive components and stored energy.

Local station is asking if they could co-locate at a weather tower, owned by the gov't. It would probably be shunt fed, 170 feet tall. The meteorologists are concerned about RF exposure as they work near the base often - once a week at least. They suggest shutting off the station each time. I could quote the 1-3 meter distance from OET-65 in my report but is this conservative or will the actual be grossly higher? 

Thanks
John Lyles