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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How do microwave transformers avoid power loss through the skin effect?

I was reading about the skin effect and how the effect increases for higher frequencies. I also read that Litz wires can be used to counteract the effect, but usually only up 1 Mhz frequency. Is ...
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Is there a soft fabric cellphone rays can't penetrate? [closed]

Do there exist any clothing like fabric which could effectively block rays from a cellphone?
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WIFI frequency and amplitude

My understanding of wifi and other wireless communication such as cellphones and radio is that there are essentially two components, the frequency and the amplitude. Different frequencies allow for ...
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Is the CHAMP missile capable of doing what they say it does? [closed]

CHAMP, A new counter-electronics directed energy USAF weapon was created by Boeing Phantom Works with the intention to damage and / or destroy electronic target equipment without causing structural ...
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What do we mean by wavelength of any electromagnetic wave?

What do we mean by wavelength of EMW? Wavelength of oscillating electric field or the oscillating magnetic field? Or is it that both the electric and magnetic field waves have same wavelength? If ...
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Considering the history of microwave Background radiation, was it ever in visible range? When will it fall to be able to heat water like in our oven?

Please do provide assurance of what formula you used and that you did the calculations for the answer. Thanks. My back of letter calculation says that CMBR was never in visible range since it became ...
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Why does a tube of frozen yogurt heat at only one end in a microwave oven?

The tubes of yogurt have a shell of thin plastic, with a single lengthwise seam and sealed at each end symmetrically apart from a small cut to initiate tearing at one end. They are of internal length ...
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Research that explains why it‘s fine to microwave a spoon but not a fork

I‘ve found plenty of articles explaining this and understand that it has to do with voltage differences at sharp corners of the object, but could find no direct research sources. Does someone know a ...
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Why and how does a microwave cavity confine resonant frequency inside it, not other frequency waves?

In microwave oven, the dimension of the chamber is determined according to 2.45 GHz frequency (or 12.2 cm wavelength). The chamber is made of metal and it should reflect all microwaves. Why does this ...
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Why do metal object in the microwave heat up while the walls stay cool?

I just came accross Why is Microwaved mac & cheese burnt where they touch? and discussed it with a colleague. We understand that metal objects heat up due to the eddy currents induced by the ...
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Is there a difference between metal waveguides in microwave frequencies and dielectric waveguides in optical frequencies?

Do they work the same way? Do metal waveguides in MW also work through total internal reflection like in optical waveguides?
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Sci-Fi weapon: Satellite shooting laser beams down to earth? [closed]

The range of one of these is stated to be 700m. Since it sends out electromagnetic waves the only problem I see with limited range is the beam divergence. Atmospheric absorption is minimal so slapping ...
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Is there any danger standing in front of a household microwave? [duplicate]

I have noticed that on the door to microwave ovens there is a metal gridded screen. Is the purpose of this screen to construct a Farraday cage so none of the radiation can escape? If so, does this ...
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How do ionizing and non-ionizing radiation interact with each other?

Given an ionizing radiation $ X $ and given non-ionizing radiation $ Y $, how does this radiation 2 interact with each other? For example I have X-rays (ionizing radiations) and Microwaves (non-...
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How cavity magnetron works?

I've found an explanation on explainthatstuff.com. There are these electrons from the cathode that are going around in a circle (because of the magnetic field), passing next to the cavities. Then it ...
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Where in microwave ovens things warm faster?

I want my mug to boil as soon as possible and I prefer not to throw energy away. Where in microwave ovens things warm faster?
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What is the difference between the microwave photon and microwave radiation?

I'm new in quantum optics and I need to know that when a detector operates in microwave frequency range, which of microwave photon or microwave radiation takes part in detection? I suppose that the ...
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Microwave cooking

This is just a little curiosity I've had, and I wonder what y'all think: I am poaching a chicken egg in a small (about 4 in. diameter) glass dish in my microwave. Let's assume the microwave is set on ...
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Which wave is widely used in waveguides?

I've studied that the rectangular waveguides are widely used because they have less cut-off frequency and as we know that the cut-off frequency is one of the major factors for waveguides. The article ...
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Radar waves all waves not working under water

was just wondering why all waves don't work under water for? I know they work for 10 meters "but" after that they don't. Does it have anything to do with it's wavelength? Or is it just that the ...
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EM/Microwave interaction with neutral atoms and their particles

I'm not sure I understand this well, so please bear with me. I've read a few answers on here about electric fields from neutral atoms, but they aren't agreeing on it. In any case, these are the ...
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Is the polar nature of water a factor in its resonance with microwaves?

This schoolphysics webpage discusses some information regarding the heating of water using microwaves, and according to that page a common misconception that "Microwave ovens operate at a ...
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Can you Split $\rm CO_2$ using Microwave Heat?

I'm a layman, so maybe I didn't put the right searches in google to find the answer, but - If you microwave $\rm CO_2$ (Carbon Dioxide) to a sufficient temperature then can you split it to $\rm C$ ...
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Microwaving two products based on individual instructions

Suppose I have a cake, which has instructions to heat it for 60 seconds in the microwave. I also have some custard, which has instructions to heat it for 30 seconds in the microwave. For convenience, ...
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Distance of electromagnetic waves based on frequency

I would like to ask your opinion regarding this matter: Based on the relation of frequency and wavelengths, the higher the frequency, the shorter the wavelengths and therefore the distance of travel ...
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Electromagnetic cooling

Heat means stored kinetic energy in matter. Microwave owens and induction heaters works on increasing kinetic energy on matter. Is it possible to make inverse of this heaters like cooler. Can we ...
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Energy variations of cosmic background radiation

Has anyone been able to measure a difference in the energy density of Cosmic Background Radiation in a gravity well compared to zero gravity?
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Why would a sweeping LIDAR or RADAR beam not produce an artificial Doppler shift?

Assuming a bi-static Radar or LIDAR with a stationary transmitter and a stationary target and a stationary receiver, with a sweeping RADAR/LIDAR beam reflecting off a stationary target: Why would the ...
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Microwaves and metal poles

I have an experimental setup like so: And if one looks closer at the lens, there are metal poles near the bottom of the lens (the extensions of the stands beyond the clamps) that are obstructing the ...
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Are normal light waves more dangerous than WiFi radiation? [closed]

I'm getting sort of tired of all the "wireless hysteria", so I thought this might be a nice comment. To the extent of my knowledge, WiFi uses microwaves, which have a lower frequency and hence carry ...
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How do microwave kilns work?

I have recently been doing some research into the working principle of a microwave kiln, and have run into a few things that continue to confound me. The first of which being that the devices ...
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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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Surface Roughness of a material in CST

I am adding an aluminium with a rough surface in CST Studio, but there is only thickness input (how thick the rough surface is), but as per ISO standards they are different types of rough surface with ...
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Ferrite material in CST Studio

I want to add a ferrite material in CST Studio for shielding effectiveness simulations, but not able to find any dispersion data for the material. I want to add a ferrite material in CST Studio for ...
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Why does a cold glass container when heated in a microwave breaks down? But a container at a room temperature does not?

I have noticed that when I take some eatable kept in a glass container, out of the fridge, when they are already at a low temperature (around 3-4 degrees) and then try to heat it up in a microwave ...
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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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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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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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Why microwave oven makes dried bread soft?

This is an old age trick: if you have some bread that became dried and you put it in the microwave few tens of seconds (10 to 30 for top results) you get a nice soft and warm loaf as if it just came ...
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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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Waveguide horn antenna & inverse square law

With a lab waveguide / horn antenna setup similar to image (without bends), we made the following measurements. Now we thought this could be used to demonstrate the observation of the inverse square ...
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Magnetron Tube Emit Direction

for a project I am doing research on microwave ovens and their operation. I have researched most of the electronic components but I was wondering about one part, the magnetron tube. I have looked it ...