Questions tagged [microwaves]

Microwaves, broadly defined, are electromagnetic radiation with wavelengths ranging from one meter to one millimeter; or with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). This range includes both UHF and EHF (millimeter waves) and the entire SHF band (3 to 30 GHz, or 10 to 1 cm).

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Attenuation in microwave and optical communications

I have read that the attenuations of microwave transmission lines and optical fibers are ~1 db/m and ~ 0.2 db/km, respectively. I understand that these values depend on the geometry, design, and ...
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Concept of polarization in microwave rotational spectroscopy

I am trying to understand the concept of polarization of molecules after they are excited by a microwave pulse. The context is: The complexes are produced in a pulsed supersonic jet expansion of a ...
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Existing microwave trapped ion quantum computer?

In the recent paper Blueprint for a microwave trapped ion quantum computer, the authors envision a scalable design for a quantum computer, built from smaller ones implemented on silicon wafers, "using ...
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What is the lowest energy atomic transition ever detected and identified?

In this concise and insightful answer to Which is larger, all known, bound nuclear energy levels, or known, bound atomic energy levels? it was pointed out that atoms can have an extremely large (...
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Why do rings form on microwaved CD/DVDs?

Here's a microwaved CD. As you can see, the disc has been destroyed, but there are very clear circular rings bridged with lines. Why are rings formed when microwaving discs?
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If I made a double slit using microwave oven door, do I get an interference pattern?

Imagine the following setup: A microwave oven door with 2 holes big enough for the wavelength of microwave to pass through, high power magnetron as the source of microwave and wall of metal to produce ...
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Subwavelength aperture vs microwave oven mesh

I am trying to understand why some subwavelength apertures radiate such as https://lo.epfl.ch/wp-content/uploads/2018/08/OE_14_10410_Oct2006.pdf and why others don't. For eg. the mesh inside a ...
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Are microwave-generating devices (gyrotrons) in the ITER system phased to heat plasma?

Provided electricity from grid is converted and supplies 24 gyrotrons, which generate electromagnetic waves, which in turn, will transfer their energy to the electrons of the ITER plasma to heat it up....
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Does a MASER beam stay un-dispersed like that of a laser?

We know that a laser beam has a very low dispersion rate. Does the same apply for a MASER (Microwave Amplification by Stimulated Emission of Radiation) beam?
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In theory, Is it possible irradiate a blob of matter -for instance- with microwaves in order to that matter emit more energy than has received?

Suppose that you want coerce a block of matter to lose his energy. I mean thermal energy. This should be done by irradiation of more energy. The final thermal energy should be lower that the original ...
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Can a microwave oven induce an accumulation of static charge in food?

I often "touch test" microwaved food to see if it is heated up enough to my preference. In doing so, I sometimes notice the characteristic tingle of a static discharge between the food and my finger (...
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Transmission coefficient in microwave cavities

I have a trouble finding the transmission coefficient S in the given case below. I am an undergraduate student and this is an exercise handed to me by my supervisor, which I haven't yet to get around ...
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269 views

Why the fields of the quasi-TEM mode of microstrip line tend to concentrate in the dielectric as frequency goes higher?

A microstrip line is a waveguiding structure as shown below: Because of the inhomogeneity, the fundamental mode of propagation is a quasi-TEM mode, which means that the z components of the E and H ...
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Do metals have negative permittivity(real part) at microwave frequencies?

I have been studying metamaterials from "ELECTROMAGNETIC METAMATERIALS:TRANSMISSION LINE THEORY AND MICROWAVE APPLICATIONS" by Caloz and Itoh. They have commented that metals at optical ...
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Faraday cage for 5G?

I'm interested in making a faraday cage that will block both standard and 5G wireless signals- essentially to make a tabletop box that people can put their phone in to be completely undisturbed, and ...
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How can I beforehand determine whether a material is a good candidate for a microwave sensor?

Is there a table of some sort or formula where I can determine before I test the material under a microwave sensor whether it will allow the microwaves to pass through and if so at what depth. for ...
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31 views

Why does Skywave only work for a small frequency band?

So it is often said that waves in the HF band (3-30MHz) use skywave propagation to beam signals around the curvature of the Earth. My question is why is there this narrow limit to what is able to ...
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211 views

Electromagnetic wave patterns in waveguides for different modes like TE10, TM11

I have read about different waveguide and their different modes like TE10, TE11, etc. In many books, the EM wave patterns are given, where they were said to be drawn from the waveguide's equations. ...
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What is the formula for the wavelength of radiation produced by non-relativistic electrons travelling through an undulator?

Is it simply equal to the length of the undulator periods? Or does it depend on the electrons' velocity and the strength of the magnetic field? Thanks.
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Time Domain Reflectometer

How can I analyze the data time domain reflectometer measurement from this picture?
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What are the properties of the electromagnetic radiation from a magnetron?

There are different modes of EM radiation. A bulb emits photons in a wide range of wavelengths and without polarisation. Radio waves are polarized modulated radiation. What is about the radiation ...
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289 views

Are microwaves sinusoidal or is that just a model?

I know that projectiles are parabolas because I can derive that from constant acceleration. And the height of a Ferris wheel rider vs. time is demonstrably a sine wave. What is the underlying thing ...
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Field at exactly the cutoff frequency of a waveguide

What happens below or above a cutoff frequency is very well documented! I have never seen though a clear explanation (as a matter of fact no explanation) about what happens at exactly the cutoff ...
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How to experimentally orient the rotation axis in the Bloch sphere during Rabi oscillations?

Rabi oscillations are well known in the field of quantum physics. I have seen plots of experimental realizations of Rabi oscillations. However, I do not understand how to manipulate the rotation axis ...
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When an electrical field is generated inside a Faraday cage (say as in a microwave) does the cage act as a reflective surface to amplify the field?

I am familiar with the concept that electrical fields within a Faraday cage do not extend outside of the cage and that electrical fields generated outside do not extend into it. My question is -- when ...
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Scattering parameter oscillation

Why does scattering parameter $S_{11}$ for a two port measurement with a simple cable oscillate with frequency?
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Microwave effect

I'm new to the forum. I state that I am a technician and I have to deal every day, even with various types of radar, but I am not only concerned with this. I found out on the web about the danger of ...
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Can we make a microstrip analog of a 3D microwave E plane Tee

I need to make the 2d analog of a microwave E plane tee.The microwave Eplane tee has 3 ports and it divides a wave input at port 3 into two 180 degree out of phase waves at the 2 output ports. I want ...
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Microwave from helmholtz coil

Can I create a microwave field in the center of a pair of helmholtz coils if I drive them at 3 GHz or will the electric component of the field cancel out?
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Microwave relay antennas

Looking over the history of microwave relays I can see there are four distinct antenna design "periods". The very early systems used simple parabolic reflectors with dipole antennas, often ...
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How does a microwave steamer work?

While I am no physicist, I am convinced this is a physics question: How does a microwave steamer work? It seems like a scam to me. Wouldn't the microwave be cooking the food and heating the water at ...
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Multiple frequencies microwave heating

I was wondering how to calculate the power dissipation density (electromagnetic losses) when two waves of different frequencies are used simultaneously to heat a dielectric object. Of course, this ...
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Microwave heater for heatin graphite crucible

I'm interested in melting alumina in a graphite crucible, some details here. As a tungsten heating wire apparently will oxidize rather quickly in a regular atmosphere, i was wondering if i can't heat ...
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In a rectangular waveguide, how can one determine if any propagation modes exist?

I'm currently studying microwave engineering, and I came across the query mentioned above. I know that rectangular waveguides use TE(m,n),TE and TM modes, but I do not understand how these modes came ...
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Superposition of Microwaves experiment? How does it work?

Please can someone help me out with this experiment and see if this is correct? So the experiment consists of one metal sheet that fully reflects microwaves (and is fixed in its position), and the ...
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How to read a meter for radio and microwaves?

I am not clear on how to read this meter for radio waves and microwaves. The bottom band shows it measures from .01 to 1. First, I'm not sure what the units mean (mW/cm2). Radio waves are from 30KHz-...
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Klystron output voltage, cavity physics

Can you please explain why almost nowhere do I see such a parameter as the output voltage from a klystron, it's easy to find the DC accelerating voltage of the beam and the electron bunch densities ...
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Why does a wave of single frequency travelling through the waveguide has group velocity?

Suppose we have a waveguide which is fed with electromagnetic wave having a single frequency of say 4GHz, if we are given the cutoff frequency we can determine the group velocity, but in order to ...
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Is there any factors depends for electromagnetic waves?

I am staying in hostel. One person said me that he is getting better connection with the wifi when the door is opened. I am wondering that what an electromagnetic wave can do with the door? Is there ...
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What factors affect the amount of microwave absorption?

I am planning to do an investigation on factors affecting the amount of microwave absorption. I understand how microwave radiation heats objects, but do factors such as color affect the amount of ...
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Reflection Coefficient --- propagation over a plane earth

In Section 2.1.2 "Propagation Over a Plane Earth" of [1], the author wrote: The reflection coefficient, $R$, of the ground depends on the angle of incidence, $\theta$, the polarization of the wave, ...
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Does the microwave generating component in a microwave operate under the same physics as an antenna radio transmitter?

Essentially does the component of a microwave which generates those microwave photons operate using an AC power supply connected to a broken circuit which causes an oscillating dipole to radiate ...
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Do conductors reflect Wifi signals? If so why?

I know electric field can't pass through conductors, but I have seen people surround their wifi router by soda can (not entirely) for better signal strength. I want to know what really happens there.
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How to devise a microwave power sensor?

I am fairly aware of the general thermistor/ diode/ thermocouple methods of sensing microwave power. Currently my requirements are simpler: A device that senses only microwave power incident on it - ...
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Mode expansion inside a waveguide

In the classic book by Collin (Foundations for Microwave Engineering, 2nd ed.), the author postulates on p. 278 that, given a waveguide structure that stretches along the $z$ axis with open ends (see ...
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Transmitted energy and transmitted wave phase in microwave structures

I have two questions about waves in large microwave structures. So the system I'm currently working on can be simulated as lossless transmission lines put together to one long structure. Without ...
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430 views

Hydrogen & Noble Gases in a Microwave

I was watching some Youtube videos of people microwaving helium and neon in a microwave. I could not find anything showing hydrogen in a microwave. However, as I was watching the videos I noticed ...
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What are the possible dangers of removing the microwave shielding?

Would removing the shielding from a domestic microwave door allow the microwaves to cause damage to a consumer grade video camera, and if so, what damage would it cause?
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Phase noise measurement with an IQ mixer

I have a question regarding a measurement scheme of phase noise that I'm trying to implement. The idea is that I have two identical signal generators (I actually do) that generate a sinusoidal voltage ...
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673 views

Loaded Quality Factor

I came up with an expression for the reflected power of a resonator: $$\left| \Gamma \right|^2 = 1 - \frac{1-\left(\frac{\kappa - 1}{\kappa + 1}\right)^2}{1 + 4 \left( \frac{Q_U}{(\kappa + 1)} \frac{\...