Let's say I have a circuit connected to an antenna which listens for a certain frequency range. The antenna would generate an electric current. For an electromagnetic wave we have two main properties- Frequency (or wavelength) and Intensity.
I would like to know what property of EM corresponds to power (electricity). What I mean by this is that does frequency corresponds to voltage (i.e. higher frequency would generate higher voltage) and intensity corresponds to current(i.e. higher intensity would generate higher current), Or the other way around?
The same question for generating EM waves- More voltage would produce higher frequency and more current would produce more intense EM waves or the other way around?
Or am I thinking about it in a wrong way? I guess a different way to ask it would be -in a circuit for detecting EM waves, How would I measure the frequency and how would I measure intensity of that wave? Or while generating EM waves, how would I control the frequency and how would I control the intensity of the wave?
Electrical – Relation between EM frequency/Intensity and voltage/current in a Circuit
antennaradioRFwireless
Related Solutions
Don't worry about photons unless you want to venture into quantum physics. A photon is the quantum of electromagnetic radiation, which is also a wave. I've yet to find an application in RF engineering where quantum effects are relevant.
In all electronic circuits, there are two fields: an electric and a magnetic. The electric field is associated with voltages, and the magnetic with currents.
We have components that make strong electric fields: capacitors.
We also have components that make strong magnetic fields: inductors.
In each of these components, we think of one kind of field as dominant. But consider what happens if we rapidly change the magnetic field through an inductor, say by passing a strong permanent magnet through it: a voltage will exist between the terminals of the inductor. This voltage is an electric field. We call this Faraday's law of induction.
A similar thing can happen to a capacitor. To change the electric field, there must be a current. Or if you manage to change the electric field, you will find a current somewhere. Manipulating the electric field inside a capacitor is rather more difficult than dropping a magnet through a coil, but if you can construct an appropriate experimental apparatus, you will find this is true.
Thus, a changing electric field can create a magnetic field. A changing magnetic field can create an electric field.
Electromagnetic radiation is these two fields creating each other in free space. The electric field changes, creating a change in the magnetic field just in front of it, creating a change in the electric field just in front...
To get these fields to radiate away in free space like this, you must create both, in phase, perpendicular to each other. This is why a capacitor is not a good antenna: it creates a strong electric field, but the magnetic field is relatively small. It radiates a little bit, but mostly the energy is stuck in the electric field, unable to radiate away because it has no magnetic field to carry it away from the capacitor. Same is true of an inductor, with current and voltage, magnetic and electric exchanged. See Why is an inductor not a good antenna?
Antennas are just leaky inductors or capacitors. Many antennas are equally both at the same time, such that their impedance is purely resistive at the design frequency, rather than inductive or capacitive. Through clever geometry, they create magnetic and electric fields perpendicular and in-phase, which then radiate away.
It depends on the Q of the transducer coupled to the medium.. it's not a characteristic of transducer alone. If the Q is very high the response will be very sharp around the resonant frequency.
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Best Answer
In an EM wave, there are actually 3 characteristics (actually there's even more, but they aren't as important here): frequency, electric field strength and magnetic field strength. The "electric" and "magnetic" components of the wave is why it's called an EM ("electromagnetic") wave. the E component can be thought of as related to voltage in a transmission line, and the M component related to the current flowing in that transmission line. The E and M components are related by the characteristic impedence of the medium through which they are travelling. (Interestingly, even a vacuum has a characteristic impedence for RF/MW.) Like electricity flowing in a wire, the power in the wave is proportional to the product of the electric and magnetic field strengths.
So, to get back to your question, in an RF wave, frequency does not correspond to voltage, in general. And both the voltage (electric field) and current (magnetic field) have corresponding intensities.
Just to confuse things and (almost) completely change the topic, there is a fundamental physical relationship known as Planck's equation, and is expressed by the equation E = hν. Here, "ν" is the Greek letter "nu" (not the English "vee", even though in this website's font it looks the same), and represents frequency. "h" is known as Planck's constant, and E is energy. So here it seems like the energy is proportional to frequency. But this relation only holds on an atomic scale for a single "photon" of energy, which is a much, much smaller quanta of energy than anything we measure in electric circuits or communications. So although Planck's equation might look like it's related to your question, and may even be the origin of your "frequency corresponds to voltage" statement, the scale of Planck's phenomenon is far too small for consideration in normal RF and MW applications.