Can I send an electromagnetic wave to a specific point?

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Discussion Overview

The discussion revolves around the feasibility of sending an electromagnetic signal within a specific frequency range (250 kHz - 500 kHz) to a precise point in a room, with a maximum error margin of 1 cm. Participants explore the theoretical and practical implications of achieving such precision in signal transmission.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the clarity of the original problem, asking for more details about the intended application and whether a single frequency is desired.
  • Another participant suggests that achieving a directional signal at the specified frequencies is highly challenging, noting that electromagnetic signals at 250 - 500 kHz tend to propagate in all directions from the antenna.
  • It is proposed that creating a directional antenna for such low frequencies is nearly impossible, and that higher frequencies would be required for more directional transmission.
  • A suggestion is made that using a laser could potentially meet the narrow beamwidth requirement, as lower frequencies would result in a broader spread of the signal.
  • One participant compares the situation to shining a light down a microscope, indicating that the ability to create a small spot is limited by the wavelength, which in this case is significantly larger than the desired precision.

Areas of Agreement / Disagreement

Participants generally agree that achieving the desired precision with the specified frequencies is problematic, but there is no consensus on the best approach or the feasibility of the original proposal.

Contextual Notes

Participants express uncertainty regarding the definitions and parameters of the problem, particularly in relation to the desired frequency and the nature of the signal propagation.

nlopwer
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TL;DR
I want to know if it is possible to make and send an electromagnetic wave to a specific point in a room.
Since I'm computer engineer and don't have much experiences with electromagnetism, I'd like to know if it is possible to make an electromagnetic signal (250khz - 500khz) and send it to a point (with an error of maximum 1cm) in a room. If yes which devices do I need to setup my experiment?
 
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Your problem is ill-defined. Do you want a single frequency? Do you want signal zero outside yourr 1cm?
Why don't you take a step back and describe what you are actually attempting to do.
 
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nlopwer said:
TL;DR Summary: I want to know if it is possible to make and send an electromagnetic wave to a specific point in a room.

Since I'm computer engineer and don't have much experiences with electromagnetism, I'd like to know if it is possible to make an electromagnetic signal (250khz - 500khz) and send it to a point (with an error of maximum 1cm) in a room. If yes which devices do I need to setup my experiment?

As Hutch said ... you problem is a bit il-defined
But going on what you have stated so far, the answer would be, no.
A signal somewhere in the range of 250 - 500 kHz, the radio/EM signal is going to
propagate out in many/all directions from the antenna ( depending on the style of antenna)
Making a direction antenna for such a low frequency would be near impossible.
The higher the frequency, the easier it is to make a signal directional, but even up into
the 10's of GHz, it's still going to be a very broad beamwidth over the distance of an average room
between the TX and RX. Really narrow beamwidth wouldn't really come into a usable possibility
till freq's in the 100's of GHz - THz range.

The ONLY way that it would be possible, off the top of my head aware of for such a narrow constraint in beamwidth, a cm or so would be a laser. Anything considerably lower in frequency than that of ""light"" IR, VIS or UV, via a collimating lens, is going to spread out and pretty much fill the room.

cheers
Dave
 
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It's rather like shining a light down a microscope to create a small spot. We can't make the spot much smaller than the wavelength, which in the present case is in the order of 1 km.
 
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