Radios receiving signals don’t just siphon the signal off lol

What you’re asking would only really happen with wireless Internet service and it’s not because of the wireless signal, but because the overall bandwidth diminishes the more people connect to it.

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11 points

I mean, literally there has to be at least a tiny amount of energy transference right?

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14 points

It’s like solar energy. You either absorb it with a panel, or it goes to “waste”. You’re not really stealing it from someone else, as long as you’re not getting too much in the way

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2 points

Usong your analogy i think Ops question was really if you have a stack of transparent solar panels will the panel below get less power and the answer is of course it will. If one antenna is behind another there will be a small reduction in the power of the signal reaching it, probably very small but with enough of them you could theoretically construct a faraday cage of sorts.

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Actually, the waves emitted by the radio tower are enough for a receiving device to generate a small electrical current just through the oscillations of the propagating signal.

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5 points
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The current produced in the antenna does (induce a field which goes on to) cancel the wave out a bit. Not enough to be noticeable in the far field, for a normal-sized antenna, but some. Conservation of energy, right?

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1 point
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Yup. It’s typically amplified quite a lot in the receiver, and the vast majority of power transmitted never is received, so it doesn’t usually matter, but it’s not a dumb question.

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56 points

Imagine you are with a friend on the beach., side by side on the water and a big wave comes. Do you fell less pressure because your friends is by your side?

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52 points

Well yeah. That’s one of the benefits of a good friendship.

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18 points

How friendly we talking about?

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4 points

Strong force friendly

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9 points
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Deleted by creator
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11 points

If they’re really close to you or the waves are small enough to block, yes. Otherwise, no. It’s a great analogy.

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3 points

A laymans opinion on the challenge: Waves lose energy, and the exact placement of antennas will matter. I don’t know what the mechanism is called, but we don’t place wind turbines right next to each other. That is afaik because each turbine takes some of the energy out of a larger chunk of the wind-wave in an ‘bubble’ around it, so we place them with optimal distance according to efficiency of that mechanism. If I’m right the effect will probably be minimal. Anyway, just a stab at an interesting thought…

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3 points
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Yep. It’s called near field and far field in radio. In the far field you can approximate it as a beam from the transmitter, while in near field it’s magnets and things can absolutely interact. You never want to put up a stand-alone antenna in the near field of something conductive. Those big tower antennas actually incorporate the ground as a critical part of their design, because of that and the non-negligible conductivity of ground water.

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54 points

Ham radio operator here: basically neither will happen because both don’t really mean anything.

This is an imperfect analogy, but I think it will set you thinking in the right direction: If someone is blinking a flashlight at you, and you’re sitting right next to another person, do both of you see the flashlight at 100% brightness, or do your eyes wrestle for the same light waves?

What does “pick up the signal at 100%” mean? Let’s say me and my buddy are talking on our car radios, no repeaters just point-to-point. If we start off in the same parking lot, we can easily hear each other. If we start driving in opposite directions, we’ll still hear each other just fine, until one of two things happens: We go on either side of a hill or far enough to be beyond the horizon, and then abruptly stop hearing each other, or the signal will fade in intensity until the background noise is louder.

If we get to that point where the signal is weak but still receivable, increasing output power of the transmitter, or switching to a directional antenna might help. People tend to think antenna gain is some magic that makes the radio louder, but it’s not. A high gain antenna does the same thing that cupping your hand behind your ear or around your mouth does; it puts more of the energy that would have gone in different directions in the direction you need.

Without getting too far into antenna theory, I will say that yes having two antennas near each other can cause them to interfere with each other. “Wrestle for the same radio waves” isn’t the way I would describe it. Antennas resonate with radio waves, it’s like a tuning fork, if you play the note the tuning fork is tuned to, the tuning fork will start to vibrate and emit its own sound. If two antennas are quite close together, this can cause destructive interference. You can use the same principle to construct a high gain antenna; look up how yagi antennas work for more details.

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2 points

If you don’t mind a followup question, what’s happening when a signal clears up if you touch or just hover near an antenna?

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3 points

possibly several things but my first thought is your body is acting like a capacitor to ground. I’m guessing you’ve noticed this on an FM radio or rabbit ears on a TV that probably weren’t grounded well.

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2 points

That can be for a few reasons…

In some cases you’re tuning (or detuning) the antenna capacitively.

On other cases, like if your tv gets interference when you’re standing in part the room, there may be standing waves causing interference, as the rf is bouncing around your room.

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1 point

To further your point, theorically, there is a voltage potential between any two objects. That’s the capacitance. Better conductor, for the same surface area, create a bigger potential.

So when you tune/detune a signal with your presence near the antenna, it is because you are close enough to the antenna that the potential between you and the antenna affects the filter of the signal.

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1 point

IF’s might heterodyne

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