Questions tagged [antennas]
The interfaces between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. Antennas are essential components of all radio equipment.
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Radio antenna producing waves in the visible spectrum [closed]
If a radio could produce waves in the visible light spectrum, what would the result be?
This is a thought experiment that I've pondered for a few years now. I realize there are a few/many real-world ...
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Quantum description of radio antenna
I am trying to form a clearer picture of how a radio transmitter emits waves from a quantum point of view.
The classical description is quite easy: the electrons oscillate in the antenna and, as ...
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Can I use an antenna as a light source?
Can I use a normal metal antenna to emit visible light?
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How do you make a spherical radio wave?
A vertical rod, a usual dipole, produces radio waves in the horizontal plane, mostly in two opposite directions:
$\qquad \qquad \qquad \qquad \qquad $
If that is possible, how do you produce a ...
user104372
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Does a radio receiver "collapse" a radio wave function?
Does a radio receiver "collapse" a wave function when listening to a radio broadcast generated via a transmitting antenna?
Background:
There has been much discussion on this forum (here) ...
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Radio waves and frequency of photon
How radio waves create the current in antenna in terms of photons? If it is Compton scattering then why is not changed the freuency of photons?
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Why are longwave radio towers so tall?
They are often in the hundred meters high. See the wiki link:
https://en.wikipedia.org/wiki/Longwave
Why are they so tall? Because the wavelength is long, so the antenna should also be long? But to ...
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Propagation of EM waves through antenna
I read in the book that when we apply high-frequency signal to a conductor, the signal propagates as a sinusoidal current in a conductor. But when the
conductor is connected to the antenna, the signal ...
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Why is the half-wave dipole the most used antenna design?
When producing em waves using a dipole antenna (of length L), you could theoretically use any L and adjust the frequency of the oscillating voltage to get the desired wavelength. Then why are most ...
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Radio antennas that are much shorter than the wavelength
From my limited experience with ham radio when I was a kid, I expect transmitting and receiving antennas to have lengths that are on the same order of magnitude as the wavelength, and in fact I recall ...
user4552
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Detectability of interstellar messages
Recently a debate started whether it is a good idea to send more messages into space in the hope of having alien civilizations receive them. There are some predecessors, most notably the 1974 Arecibo ...
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How can current flow through an open wire (like a dipole antenna)?
I am trying to understand how current can flow through a dipole antenna (with length $\frac{\lambda}{2}$ or anything else) which actually is nothing more than an open wire.
Could someone clarify this ...
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Has anyone ever put a magnetic or electrostatic dipole on a rotating shaft, spun it and demonstrated reception of a propagating wave in the far-field?
The question If I create a varying electric field and it will then create a varying magnetic field, so will it also create light? Will I see a light ray? got me thinking.
I'm pretty sure that if I ...
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How a dipole should behave in order to produce an electromagnetic field?
I am trying to understand what an electric dipole "has to do" to produce electromagnetic waves. I know that an oscillating electric dipole will produce EM waves and by oscillating electric ...
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What happens when length of antenna >> lambda
Length of a dipole antenna according to antenna theory should be lambda/2 for best reception. I am just curious about the outcome when length of dipole antenna >> lambda. Impedance will be zero in ...
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