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Post by Deleted on Aug 29, 2017 0:10:09 GMT
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Post by mark on Aug 29, 2017 4:02:23 GMT
Good article, very informative.
Mark
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Post by Deleted on Aug 29, 2017 15:53:35 GMT
Also Paraphrased from Part15_US
Artisan Radio: "The Talking House instructions state that if you are going to locate the wire antenna indoors, it should be in the center of the house, on the 2nd (or, presumably, higher if you have one) floor. It should not be strung up in front of a window, as glass (they claim) blocks RF in the AM range."
So I'm wondering, is that really the case? And what else would block (or at least diminish) AM signals (other than metal). PVC? Wood? Gyprock?"
The technical information linked above proves Mark is right by saying that the Talking House Instructions are wrong, but what we learn is inconclusive:
"Example: Some light reflects from the surface of clear glass and some light
travels through the glass. The same is true for clear glass and radio waves."
How much is "some"?
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Post by Druid Hills Radio on Oct 3, 2017 15:16:23 GMT
Also Paraphrased from Part15_USArtisan Radio: " The Talking House instructions state that if you are going to locate the wire antenna indoors, it should be in the center of the house, on the 2nd (or, presumably, higher if you have one) floor. It should not be strung up in front of a window, as glass (they claim) blocks RF in the AM range."
So I'm wondering, is that really the case? And what else would block (or at least diminish) AM signals (other than metal). PVC? Wood? Gyprock?" The technical information linked above proves Mark is right by saying that the Talking House Instructions are wrong, but what we learn is inconclusive: " Example: Some light reflects from the surface of clear glass and some light
travels through the glass. The same is true for clear glass and radio waves." How much is "some"? The School of Business building here at Saint Leo University has window glass that is tinted internally to reduce the cost of heating and cooling. The tint makes the use of cellphone impossible when inside the building. |
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Post by Deleted on Oct 4, 2017 2:39:53 GMT
That's because the tinting is usually metal-based.
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Post by Deleted on Nov 5, 2017 20:27:04 GMT
The problem is AC electrical wiring in the walls, especially wiring going up the wall to light fixtures. The vertical AM BC antenna inside the house couples to the vertical AC wiring, inducing RF current into the wires. The magnetic field caused by the downward RF current in the AC wires partially cancels the magnetic field caused by the upward RF current in the antenna. The result is reduced antenna radiation resistance and less radiated energy.
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Post by Deleted on Nov 5, 2017 20:48:34 GMT
Agreement is a Welcome Experience
I completely agree with DaveC: "The magnetic field caused by the downward RF current in the AC wires partially cancels the magnetic field caused by the upward RF current in the antenna. The result is reduced antenna radiation resistance and less radiated energy."
This same rule-of-thumb applies to a "ground lead", that is, a wire aimed vertically downward from transmitter ground and (as in my case) clamped to a steel I-beam which makes contact with criss-crossing metal ductwork and a heavy copper wire between the electric panel and the cold water pipe. The zig-zag and back-and-forth of all the grounded metal suffers much attenuation from the many out-of-phase instances.
I bring this up because I've been disagreed with about this.
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Post by Boomer on Nov 6, 2017 1:15:14 GMT
I notice the same effect as Davec and Carl, but with carrier current out in the street, where signals on different wires seem to reinforce and cancel each other. The signal strength is constantly changing as you move down the street.
I notice the signal changes very much in the house, with strong nulls and peaks when turning a portable radio from side to side, and even get loud hum in certain positions.
Boomer
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