These guidelines for working in an electromagnetic environment were on a sign on the fence of an ATT Microwave Relay freestander that I opened a couple of weeks ago up north. Most signs are general and of the "Warning levels of RF radiation past this point may exceed recommended levels for humans" or "Caution Radio Frequency Environment" variety, so I add this sign into Blinc's archives for its specificity. You cant get more to the point then this sign, and I believe you can make some deductions from reading it which may provide some insight for future discussions on the hazards of BASE jumping from antennas (FM), particularly "pro" arguments of the "if its got a ladder its meant for humans to climb, so it must be reasonably safe" variety. This is a common freestander in North America, usually 265-360 ft high (usually around 320 feet); it always has red and white paint, and has a nice big platform on top. A number of these have few or no transmitters on them; but when they do have transceivers on top, they are big, ice cream cone/shoe horn looking things, usually one at each corner of the square platform. This particular antenna had all four corners filled, plus 3 or 4 of the "drum on its side" variety of microwave transmitters at different levels of the body. On top, standing next to the large transmitters you feel distinctly warm. They dont feel warm, the heat doesnt seem to be coming from anywhere, its just if you move away from the center of the platform to go over the railing, YOU feel warm (a microwave environment). The jump was filmed. I transcribe the sign below, thanks...
NOTICE
Guidelines for working in Radiofrequency Environments:
All personnel should have electromagnetic energy (EME) awareness training.
All personnel entering this site must be authorized.
Obey all posted signs.
Assume all antennas are active.
Before working on antennas, notify owners and disable appropriate transmitters.
Maintain minimum 3 feet clearance from all antennas.
Do not stop in front of antennas
Use personal RF monitors while working near antennas.
Never operate transmitters without shields during normal operations.
Do not operate base station antennas in equipment room.
*end sign*
In the Navy, I knew some folks who worked in the radar shop (63A) who periodically came out with tumors and/or burns from operating and being near "transmitters without shields" . In 63A that meant the enlisted tech had forgotten to put a "dummy load" and cover on the transmitter or test equipment in use at full power....




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