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Not so much a propagation concern as keeping the near fields away from people. The voltage on the tuning capacitor will be of the order of many kilovolts? with a current of >10 Amps at around the 100W level. Any antenna is a transducer that converts electrical energy into electromagnetic energy. A resonant wire dipole can be very close? to 100 % efficient.? A good transmitting loop can also be efficient but the much smaller structure needs much higher E and H fields to radiate so the near field intensities are very much higher than a full sized antenna.

?A continuous screen over a roof would reduce the exposure to people underneath the loop. If it is a concrete and rebar structure there may be no connectivity between the rebar so there may be no screening for people a metre under the roof mounted loop.

Fitting a loop to a fence also implies that people on the other side of the fence can receive?? very high exposure without understanding the risks. You cannot protect children, babies or pets on the other side of the fence. So Cirro's? reply is easy to understand.

As? there are now? requirements to assess fields around transmit antennas it would be prudent to follow the recommendations. Personally I would want to keep at least 10m. away from a transmitting loop radiating 100W . Putting 2 KW into a loop puts over 4.5 times the current and voltage into the structure compared with 100 W operation. That would be enough to arc capacitors and generate huge RFI in many loops however the Cirro loops have exceptionally high power ratings with 14mm minimal capacitor plate spacings.But then the E and H fields are very high, don't worry about objects or lengths of cable- think about People and your humanitarian and legal position.

Wet trees are not that lossy, signals do not vanish when it rains even though a ground wave signal can go through hundreds of trees. Rainwater is quite pure and forms a very thin partial film on trees. Sap is a much greater attenuator potentially as it has a much larger cross section however it's not much of a problem to LF to VHF radio waves. People have used trees as transmitting antennas, not nearly as good as? 35m of metal mast but a lot cheaper. Trees have a very long history as supports for wire antennas, people don't complain about the tree getting warm but are happy to get the wire into the air.

Now that there is a requirement to consider the exposure of others in some Countries I would not ignore this need, a vexatious? group could cause a lot of trouble,? demonstrating compliance is a valuable defence and a wise precaution. Position matters.

73, Alan G8LCO.