The most often quoted FCC Rule for AM broadcasting is 15.219, with the familiar guidelines of “3-meter antenna, etc., and 100mW to final amp…”
The most often quoted FCC Rule for AM broadcasting is 15.219, with the familiar guidelines of “3-meter antenna, etc., and 100mW to final amp…”
But every once in awhile someone mentions “the alternate rule, based on field strength measurement.”
That alternate Rule is 15.209, with this regulation:
Frequency Band .490 to 1.705 24,000mV/F(kHz) at 30-meters (about 100-feet).
For AM transmitters located INDOORS there is an extra layer of filtering that just might allow MORE than a 3-meter antenna or MORE than 100mW to the final amp…
That extra filter is the HOUSE. The house is made from construction materials consisting of wood, bricks, plaster and some metal. Therefore the house should be part of anyone’s radiation study to see what the power will look like at the edge of the property, right around 100-feet away.
How can we build a chart showing predicted attenuation figures for different kinds of houses?
Wouldn’t Every House Be Different?
Carl, I have thought of this with regard to
my carrier current transmitter. Although
a friend has it now, eventually it will be
repaired. When that happens, I will
probably first put it into an RF attenuator/
antenna in the house for initial tests. The
transmitter runs about 6 watts out when it
is working right. I would keep it in my
collection even if it did not work at all.
This will not be a carrier current transmitter
for a long time. It will just be for my antique
radio collection. The expected operating
frequency will be 550 Khz because my friend
has a higher frequency crystal which he can
divide down to 550 kHz. Also, 550 is clear here.
The set-up will comply with 15.209.
Getting back to your question. Wow, it’s hard to
wrap my brain around that idea. I think you would
have to try it for your house on the frequency of
your choice, which is in the AM BCB now. There are
so many different factors involved. Not just the
structure of the house and it’s materials, but the
wiring, the furniture, the pipes, stuff in the attic,
who knows?
You might be able to get an idea with a portable
receiver that has a signal strength indicator. But
RF/EMI in the house will maybe complicate that.
Let us know what happens.
Bruce, MICRO1690/1700
That’s Not the Way It Works
No, I’m not going to let you know what happens.
I put this here so you could figure it out.
My Reply:
OOOOOOOOhhhhhhhhhh No!!!!!!!!!!!!!!!!!!!!!!!
As always, best wishes!
Bruce, MICRO1690/1700