FOR PART 15 RADIO BROADCASTING IN U.S.
This collection of technical information is dedicated to Part 15
low power radio broadcasters who erect indoor transmission antennas for
reasons of their own.
In some cases an outdoor antenna is not
possible because the necessary ground space is not available. In other
cases the operator may be prohibited from mounting antennas on land or
structures because of deed restrictions or building rules of various
A testing facility has been dedicated inside the Internet
Building utilizing an AMT3000 transmitter from sstran.com and a part 15
station established with call letters KHZ, operating at a frequency of
1640 kHz, expressly for the development, testing and documentation of
many indoor antenna designs. In some cases other frequencies or transmitters may be utilized, this will be stated.
This collection of antenna
information will be posted in the public domain, except that special
designs from contributors and external sources will be properly
attributed and those inventors made part of this record.
NEC will calculate the radiation pattern of an antenna, but it is
not the best tool to determine the effect of the passage of radiation
from indoors to outdoors.
Such effects vary considerably depending on the construction of the building, the operating frequency, and other factors.
I have a Tecsun PL310 receiver, which displays the strength of the
received signal in "dBµ." When I tune it to a local station on 1530
kHz, it reads the same maximum value no matter where I am in my house as
when I am outside the house.
On a local FM station, the radio reads about 3 dB lower inside the
house than outside, in general, but there are some places on the first
floor of the house where it reads 5-6 dB lower.
My house is a typical ranch style, brick veneer structure. Houses
with aluminum siding, stucco over a metal grid, buildings with steel
beams etc all behave differently. In some cases they can make radio
reception inside them almost impossible.