[Lowfer] Loop Question

[Lyle Koehler]

>"What is the output power limit to run Part-15 on
>136kc"???

Under the general provisions of Part 15, emissions in the 9 kHz to 490 kHz
band must not exceed 2400/f microvolts per meter at 300 meters, where f is
the frequency in kHz. At 137 kHz, that works out to 17.5 uV/m. For me, the
easiest way to relate those numbers to the "real world" is to use the
near-field option in an antenna modeling program like AO or NF, and
calculate the field strength from a specific antenna. At 300 meters from a
15 meter square loop of 1/2 inch copper with an added loss resistance of 0.2
ohms and 1 watt input, the predicted electric field strength is
approximately 1,000 uV/m. (Bill, does that agree with what you measure?)
There's a reason why LowFERs prefer to operate under the special provisions
for 160-190 kHz!

About 8 years ago there was a LowFER in Michigan who was using a loop
antenna for transmitting. He claimed that because it was a "magnetic"
antenna, the E-field it produced was very low, and he could run considerably
more than 1 watt under the general Part 15 provisions. Maybe we should find
out what calculation *he* was using :-) But I never heard him anyway...

Lyle, K0LR