Wireless Frequencies: Red Light Frequency Visible?

Click For Summary

Discussion Overview

The discussion centers around the nature of wireless signals and their relationship to visible light frequencies, specifically red light. Participants explore the implications of using antennas to transmit signals at optical frequencies and the conditions under which red light might be perceived.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants question whether creating a wireless signal at the frequency of red light (approximately 430 THz) would result in the perception of red light.
  • One participant asserts that creating red light is equivalent to creating a wireless signal at that frequency.
  • There is a discussion about the type of antenna required to transmit at such high frequencies, with some suggesting that standard antennas used in cell phones may not be suitable due to their narrow frequency range.
  • Participants mention that loosening the definition of "antenna" could allow for devices like lasers or light bulbs to be considered, although they note that lasers are more appropriate for communication purposes.
  • One participant introduces the concept of free-space optics as a potential area of interest, suggesting it operates similarly to optical fiber without the physical medium.
  • There is a technical consideration regarding the size of antennas needed for red light transmission and the challenges posed by quantum mechanical effects at such small scales.
  • Another participant expresses their limited understanding of electromagnetism and their plans to further their education in the subject.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of using standard antennas for transmitting red light frequencies, with some suggesting it is possible under certain conditions while others argue against it. The discussion remains unresolved regarding the specific requirements and implications of transmitting at optical frequencies.

Contextual Notes

Participants acknowledge limitations in their understanding of electromagnetism and the technical challenges involved in antenna design for high-frequency signals. There are also references to the physical constraints of antennas and the effects of quantum mechanics at small scales.

Goalie_Ca
Messages
102
Reaction score
0
Okay, this may sound like a dumb question, but if i were to create a wireless signal with a frequency of red light for example, how come i would not see red light... or would i? Is this a difference caused by real and virtual photons?
 
Engineering news on Phys.org
Creating red light IS creating a wireless signal with a frequency that of red light.
 
I guess what i mean to say is that if i had an antenna and i kicked the frequency up to 430 THz (somehow) would i see red light?
 
Goalie_Ca said:
I guess what i mean to say is that if i had an antenna and i kicked the frequency up to 430 THz (somehow) would i see red light?
Yes.

What type of antenna do you think you'd need?
 
If you loosen your definition of "antenna" ...
 
turin said:
If you loosen your definition of "antenna" ...
Right - a light bulb is, in a loose sense, an antenna transmitting at a wide frequency range.

edit: light bulb isn't a great analogy - laser is better. And lasers are even used for wired and wireless communications.
 
Last edited:
err, so what i meant by antenna is like a standard antenna! The type a cell phone or 802.11g card has.
 
Goalie_Ca said:
err, so what i meant by antenna is like a standard antenna! The type a cell phone or 802.11g card has.
In that case, no. An antenna like that has a fairly narrow range of frequencies it can transmit/receive in due to the physical size of the antenna and construction of the transmitter.
 
If you would like to consider the infrared rather than optical, and consider highly directional paths rather than sectors (though even mobile/wireless technology is moving strongly to beams, to increase frequency re-use), then free-space optics may be what you're interested in. The idea? Think optical fibre, without the fibre. :smile:

The 'antennae' look rather different than what's on a mobile handset. :eek:
 
  • #10
Okay, can it not transmit / receive because of capacitances in the antenna making it act as a filter?
 
  • #11
Think about how large a half-wave dipole would need to be for even red light (L = 400 nm at the longest). Then, how would you couple to your antenna? The thinnest wires I've ever seen would have a diameter on the order of the length of your antenna, and at those frequencies, you can't afford the random surface current effects that this would cause. And related to this issue, the dipole would need to be so thin that QM effects would dominate any of the CM effects that you would be trying to achieve. You're best bet is to use a diode. This is even done often all the way down to the microwave frequencies (Gunn diodes in horn antennas).
 
  • #12
I think i get what you're getting at.

My EM knowledge is, to put it bluntly, very weak. Sadly, i have to wait a while, due to the course offering schedules and my own, to take the two other courses in it that i plan on taking.
 

Similar threads

Frequency Comb (Photonics, Optics)
  • · Replies 3 ·
Replies
3
Views
1K
How Do Wireless Digital Transmissions Work and What Affects Their Quality?
  • · Replies 3 ·
Replies
3
Views
3K
Submarine communications and RF skin depth
  • · Replies 6 ·
Replies
6
Views
4K
Why is impedance given as a simple Ohms unit when it's frequency dependent?
  • · Replies 10 ·
Replies
10
Views
3K
Radio frequency shielding for Raspberry Pi Zero
  • · Replies 6 ·
Replies
6
Views
4K
Increasing the 50 Ohm bandwidth of an impedance-matched system
  • · Replies 19 ·
Replies
19
Views
5K
Minimum Frequency of FM Data / Catastrophic Error Scenario?
  • · Replies 68 ·
3
Replies
68
Views
7K
Undergrad Visible light Over Large Distances
  • · Replies 4 ·
Replies
4
Views
2K
Is my understanding of the Nyquist theorem correct?
  • · Replies 4 ·
Replies
4
Views
2K
Frequency Shift Key Modulation: how are the carrier frequencies chosen
  • · Replies 5 ·
Replies
5
Views
2K