The fascinating experience of learning how to use the new AMT5000 transmitter from sstran.com has brought the question of antennas foremost to mind, for the obvious reason that the antenna is so essential in disseminating a radio signal into the surrounding air.
The perfect starting point for me is this description of the Ultimate Part 15 Installation, written by PhilB earlier in the year:
http://www.part15.us/index.php?q=node/2728
In his posting, Phil is talking about classic antenna practice for AM radio, a proven and standard set of practices.
The trouble for Part 15 is that the typical setup is in a home or apartment, and the more industrial step of devoting real estate and somewhat of a big dig to locate an ideal 3-meter stick on cleared ground is not often an option.
Therefore something less than ultimate is needed, something of a compromise.
Indoor antennas are a common reality for many Part 15 radio stations, and this brings the question: what are the best designs for indoor AM antennas?
When I first started Part 15 about 6-years ago I used a glue stick to run the “white wire” 3-meter antenna up the same corner of the room where the transmitter and audio source were located (computer). Typical room height in most homes is less than 3-meters, about 8.5-ft.
The corner was chosen for proximity to the equipment, and neatness, because a white wire in the corner of a white room is very inconspicuous. But would the antenna have served better moved away from the corner, farther toward the middle of the wall?
The wall is the most likely place for a vertical indoor antenna, but would it work better moved into the room, away from the wall, perhaps by hanging from the ceiling alongside a floor lamp or other furniture?
Basement transmitter locations usually utilize horizontal antennas, and there are attic installations.
No full power radio station would ever place its antenna indoors, therefore no standards have been developed for such practice, but Part 15 is an exceptional circumstance, and indoor antennas are part of the game.
The question is, what are the best designs for including a 3-meter vertical antenna within home furnishing.
Some Suggestions
Try one of those tall corner lamps with the typical lamp shade as a capacitor hat. Run two ground wires as a counterpoise along the edge of the two walls away from the corner lamp/antenna.
RFB
Floor Lamp Antenna
The floor lamp antenna sounds like a very smart way to integrate an antenna into the home decor.
Most floor lamps probably have AC power running up inside the pole, would this cause inductive interference, or, possibly put the AM signal into the house wiring, e.g., carrier current?
Floor Lamp/AC Wire Interaction
“Most floor lamps probably have AC power running up inside the pole, would this cause inductive interference, or, possibly put the AM signal into the house wiring, e.g., carrier current?”
Well most tall corner lamps made of a metal base and mast will have the AC power wiring inside the support structure. Not exactly centered along the length within, but that is really no matter of concern.
But yes the AC power wiring for the lamp will have some of the signal inductively coupled onto the AC power wiring and send it down both one side of the two main HOT’s and the neutral.
So you will get the best of both worlds in just such a setup….through the air and a bit of CC.
RFB