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Pre-historic Video Amplifier Antennas useless?! Answered

I've been learning quite a bit about video amplifiers recently. And it's brought me to a question. When antennas were the source of video-signal, you would often hear horror stories of people having to get up off of their couch to adjust the "bunny ears", to get a clearer signal.

I'm just confused. Why would they have to be adjusted? The signals, if my understanding is correct, is electrical signals sent through the air, and the signal would cover thousands of feet. It surely didn't matter if the antenna was all but a few inches from one spot or another. The signal should be able to hit it just the same no matter what, correct? If you are in a car, it's one thing - you're moving. But in a house, you're stationary.

Any explanation?

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kelseymh

7 years ago

In any kind of built-up area (urban or suburban), there is no such thing as "line-of-sight." There are multiple reflections off multiple surfaces, leading to extremely complex three-dimensional interference patterns.

Since radio signals are polarized (since the transmission antenna is basically a dipole), the three-dimensional orientation of the receiving dipole antenna plays a major role in signal acquisition.

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caitlinsdadkelseymh

Reply 7 years ago

and my neighbor yells at me because he thinks I use his wi-fi.

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kelseymhcaitlinsdad

Reply 7 years ago

Wait a minute. Don't you live in New York? I thought neighbors there yelled at each other just on spec....

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caitlinsdad

7 years ago

ahem, from experience.....depending on where the transmitter tower was, sometimes you get a better signal when pointed line-of-sight to the source. If you are in the big city, you might try to align the antenna to catch the bounced off waves from buildings or do so to mitigate the interference from those bounced off signals. Depending on the frequency of the wave, a general purpose antenna may not not be optimized for the wavelength and you have to catch the wave or portion of it at its best. There is a whole lot of science behind it...but then again the fine-tuning knob was just like that button you push to speed up the walk/don't walk sign.

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freethetechcaitlinsdad

Reply 7 years ago

Hmm very interesting. I had a different title for this ("Bunny Ear adjustment useless?!"), but i stupidly put it as the keywords by accident. Anyway. I was wondering and thought it had to do with the line of sight. I haven't studied too much about waves traveling through long distances, but I know they get weaker and [larger] as they continue moving.

In one chapter of a book I am reading, it stated that if two radio station towers had the same output, they'd only vary in "loudness" by how far they are. So i guess that's how this rolls out, too.

Thanks for your responce(:

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caitlinsdadfreethetech

Reply 7 years ago

I think if two separate stations were transmitting the same thing, you would have interference and also the possibility of doubling the strength where they synch up and maybe that is why they limit power when they license a station. Visualize waves by tying the end of a long string to something. Hold on to the free end and whip it to induce a wave. Try it with two strings.... Take this and do something for the teacher ible contest as a learning point. Good luck.

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freethetechcaitlinsdad

Reply 7 years ago

Ah, my bad. I didn't mean broadcasting the same thing, i meant if they have the same output strength. I'll go back to my book and later post the exact wording.