So I’ve been trying to comprehend how wifi works, and just cannot visualise it.
I know that there is this field were surrounded by, and antennas create waves in it that can be picked up by other antennas.
I’ve been trying to visualise it similar to being underwater and moving water around with your hands, but not sure if this is accurate.
Anyway, I don’t know what this “field” is made of. Can someone ELI5?
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Wi-Fi is very similar to radio waves, and other wireless transmission communication protocols that are in use with the FCC and the IEEE, that said, it’s just a wireless signal transmission of data, not really a difficult thing to do in this day and age given how radios cell phones and Bluetooth works. if you can understand how radios and Bluetooth work, then Wi-Fi operates on very much of the same principle! It’s basically the same as a cellular signal or cellular data as to how that works, if that helps
For Wi-Fi to function you have a radio That transmits a wireless signal, based on a timing and pulse rate, and that signal that is transmitted, is picked up by a special receiver, which allows for data to pass over airwaves once the signal is received, it’s basically processing the same way that ethernet pulses over a wire work, a connection is established with something similar to TCP then data is transmitted
So an electro magnetic wave is actually two different waves, one electric and one magnetic that travel in perpendicular planes but in the same direction, or at least it can be thought of in this way. The thing that makes it different than day a wave of water is that it’s a transverse wave, meaning it’s peaks and depths are not in the same direction as the direction it’s traveling, think a sine wave moving to the right. Electro magnetic waves are very interesting because they aren’t exactly waves. They have wave like properties but they also have particle like properties. Some will say that light (which is a form of electro magnetic radiation) is both a wave and particle but that is misleading, a more accurate statement is that it is something that we have very little intuition about. Something that we have trouble conceptualizing. Something that has both wave and particle proprieties simultaneously. Another unique feature of electromagnetic radiation is that it does not require a medium, meaning it can travel even if there isn’t any matter, say in a perfect vacuum. When you get in the weeds and learn more it gets stranger, like EM radiation will sometimes disappear and become two particles, one real and one virtual which then combine together due to gravity and become EM radiation again. Other things have shown this particle-wave duality such as electrons. The Field part of EM field is more of a math term, where you can imagine a field as a three dimensional area where at any point you have an associated strength of this EM radiation.
It’s made of photons. If you could “SEE” wi-fi, a wifi router would look like a bright lamp that flickers really fast- the flickering is the data signal. The antennae on a cellphone would be a smaller light, and the antennae on a cell phone tower would be like a lighthouse flashing signals in every direction
EM radiation is just photons, it moves like light, just not the same frequency as the light that we see
All things that are called “waves” satisfy the wave equation. The wave equation tells how a field change over time. While there are significant differences depending on the space and the type of quantity, because of the shared mathematical equation, you can often visualize one field using another, as long as you’re aware of the difference and don’t carry them over.
For example, when you create pressure wave in water (aka. sound wave), these are longitudinal wave, which is different from transverse wave, in that the water move along the direction you push, not perpendicular to it. But as long as you know that, you can still think about the amplitude of the wave and they are still the same.
So first, let me talk about EM field.
A “field” is a mathematical model that assign each point in space a quantity. The “space” could be literal space, or smaller part of space, spacetime. “Quantity” are things that can be added, scaled and subtracted, which does not have to be just numbers.
Height of water over the water surface is a field: here the “space” is the 2-dimensional water surface, and the “quantity” is a number for height. Direction of air flow is a field: the “space” is the 3-dimensional space where air occupy, and the “quantity” is the 3-dimensional vector telling you where and how much air flow. You will see that physics frequently will use fields to describe things.
So what is EM field? There are actually 2 versions of it. The non-relativistic EM field is a field in which the “space” is 3-dimensional space everywhere, and the “quantity” is the pair of vectors describing electric and magnetic field. The relativistic EM field is a field in which the “space” is the 4-dimensional spacetime, and the “quantity” is a function that tells you density of “flux” through an infinitesimal “surface” in spacetime.
Let me emphasis that they’re both *mathematical model* about how electromagnetism work. Neither are accurate, but they’re very good most of the time. Non-relativistic EM field are easier to visualize and works well in everyday situation, while relativistic EM field is more accurate at high velocity situation. None of them are how physics “really” work.
So does the “pressure wave in water” picture you have been using work? Yes. For the question you have (how do I transmit information with wave on a field?), the analogy using water work just fine.
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