It’s winter here in the north, and therefore not a good time for outdoor antenna experiments. So I’ve got an idea for something to try until the thermometer rises to a more comfortable level.
It’s winter here in the north, and therefore not a good time for outdoor antenna experiments. So I’ve got an idea for something to try until the thermometer rises to a more comfortable level.
Indoor antennas are not known for great performance, but let’s see what you guys think of this idea. I have a space in the attic where I could install my SSTran. If I put the transmitter on the attic floor, I could ground it with a short wire 🙂 to one of the electrical conduit lines that distributes power to the rooms below. Potentially, I could even lay out some additional radial wires on the attic floor. The antenna wire could extend vertically about 6-7 feet (a compromise, I realize). It would be a relatively simple matter to add a top hat made of 6-8 ~1 meter long wires. The wires could be tacked to main cross beam and to the rafters. The ones along the cross beam would be horizontal, but the others would have to angle downward to accommodate the slope of the roof. I hope that that this would not significantly detract from the top hat’s performance.
It gets cold up there, but at least the transmitter is protected from the elements, and therefore would not require a special enclosure. Adjustments would also be easy to make, and it would be easy to run power and audio to the unit.
Has anyone tried something like this, and if so, how did it work out for you?
Same situation, different direction
Agreed that this is not the best time for outdoor antenna installation here in the north! I’m in pretty much the same boat.
I have some attic space as well, but what I’ve been thinking of is a coil loaded antenna tuned to resonance down in the basement where I can get a very short path to “actual dirt”. A choice of very short paths, in fact, since the electrical ground, water mains, gas line, and a rather massive furnace bolted directly into the concrete floor are all available down there.
I think Neil uses a coil-loaded antenna in the basement, but if I recall correctly I think his is positioned horizontally.
Anyway, I’m planning on an outdoor ground mounted coil loaded antenna this summer most likely, so I was thinking I can at least get the loading coil built and maybe experiment a bit with coils and tuning methods and hopefully it’ll be easy to apply to the eventual outdoor antenna.
Daniel
Basement siting
Daniel,
I also have a basement, but it is very small. In addition to being below grade, the antenna would be surrounded by large metal objects, including my furnace, a washer and dryer, large cast iron sink, and a chest freezer. This wouldn’t seem to be the best place for me to install the antenna, although as you pointed out, there is good access to grounded objects.
I think you’re correct about Neil using a horizontal antenna. It could be tried, but my car radio’s antenna is a vertical whip, so I assume there could be significant signal attenuation due to cross polarization. Also, portable radios with internal ferrite antennas would need to be turned sideways to get the best signal.
I am working on some things you might be interested in. I’ve just ordered some additional iron core and ferrite toroids to be used to make antenna matching coils. The idea is to see how close I can come to replicating the performance of the large air-wound coil in a smaller form factor. I’m going to test several core sizes and materials to see which one gives the best results. I’ve also ordered some high breakdown, small signal switching transistors as possible replacements for the ones in the output stage of the SSTran, just to see if that helps with any of the voltage-related effects that some have noticed. These two items may help improve performance.
The main issue with indoor operation is still finding an acceptable location for the antenna/ground system. Often your options are very limited, and the best spot for an antenna isn’t near a “good” ground connection. Of course, no ground connection that you can find inside of a building is likely to be an efficient RF ground– not even a water pipe– although that is likely one of the best grounds available in most homes.
I’ll let you know how my coil experiments turn out.
WEAK-AM
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