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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25 views

How I simulate this in CST Studio? [closed]

I am trying to simulate this coaxial transmission line setup for EMI shielding. Placed the Aluminium sample as seen below (in the middle). I am new on this software, learned simulating the coaxial ...
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156 views

What is the maximum speed of waves in stagnant water?

I want to learn the maximum speed conditions for a wave in a fluid. I think, Which mechanism causes this limited speed? And How? The water is an understandable example for me. By this question, I ...
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757 views

The “watering hole” frequency versus microwave oven frequency

I recently learned about the "watering hole," a group of frequencies between 1.42 and 1.66 GHz. I also read that microwave ovens operate at 2.4 GHz. If 21 to 18 cm (1.42 to 1.66 GHz) is the resonant ...
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Why plastic covers on containers are compressed when microwaved?

These situations happen a lot around me since I always bring my lunch to the school. It is not just plastic warp, but my plastic container lid too. Unlike Why does plastic wrap grow, then shrink, then ...
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293 views

Is fire more harmful than a phone?

I have read somewhere that the higher the frequency of electromagnetic radiation, the higher the damage it causes to your body, and visible light has a very high frequency in comparison to microwave ...
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2k views

Blocking WiFi with Faraday cage [closed]

As part of a project I'm trying to prevent WiFi transmission of frequency 2.4 GHz from reaching a Raspberry Pi via a Faraday cage. Would a 20 micron aluminum foil do the job?
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84 views

How could a microwave launch a cup?

This is something that's puzzled me for years and I'm hoping someone here can offer a theoretical explanation and put my curiosity about it to rest. About 15 years ago in my bachelor days I wasn't so ...
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1k views

What happens in a microwave oven with hole in the shielding?

We have a question on cooking asking about the safety of a microwave with a hole in it. The question isn't totally clear whether the hole has actually penetrated shielding or just the plastic wall of ...
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996 views

Microwave Faraday cage shielding

After a decade of using a microwave oven in my house I figured out I never cared to connect the grounding cable. So my question is regardless of electrical shock risk, does the Microwave Faraday cage ...
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111 views

Shape of metal to be heated in consumer microvave oven? [closed]

I tried to use a common 900 W microwave oven melt some alloy with low melting point (138 deg C, eutectic bismut/tin). The metal did not heat up, neither did the metal container, which makes me think ...
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202 views

How come a current sheet of $J_s = J_0 \hat{x}$ produces plane wave solution?

Given in the picture. There is a current sheet $J_s = J_0 \hat{x}$. Supposedly Jo is not oscillating. So, how does this thing create a plane waves propagating away from the current sheet? Shouldn't ...
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246 views

Microwaves and state of matter

Does the heating efficiency of a microwave oven depend on the state of matter that it heats? If yes, how?
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Cooling at a Distance

We have microwaves. Microwave ovens convert electricity into microwaves, specifically waves that resonate with water to make it hotter, thus heating my pizza in 3 minutes without disintegrating the ...
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132 views

Why does an aluminum foil spark inside a microwave oven? [duplicate]

I did an experiment today. I put an aluminum foil inside the microwave oven thinking that nothing would happen. But contrary to my expectations it started sparking badly. I looked for answers on the ...
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569 views

Standing wave ratio inside a waveguide

If there were microwaves being transmitted through the waveguide in the image below out the horn, and I place a sheet of metal in front of the horn (perpendicular to the propagation of the waves), ...
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191 views

Can a mesh shield keep food cold in a running microwave?

Please forgive my amateur physics knowledge. Say it's Thanksgiving leftover day. You load a plate with turkey, potatoes, cranberry sauce, and salad. Now it's time to heat your food, but oh no! You ...
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44 views

Generator phase noise influence on its averaged signal

I need to estimate averaged signal of a generator with known phase noise and the amplitude noise can be neglected. The averaged signal of the generator is expressed as: $$ \langle A\exp{i(\Omega t + \...
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125 views

Potato Cooking Room [closed]

In the TV show "Murdoch Mysteries" (S12E01) Detective William Murdoch has a an ultra-modern (for the Edwardian period) house built. It includes a "potato cooking room" which is essentially a broom ...
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3answers
425 views

Do microwaves break hydrogen bonds?

We're told that the photon energy of microwave frequency radiation ($\sim 10^{-5}~\text{eV}$) is not high enough to break hydrogen bonds. But if that's true, how does dielectric heating of water work?...
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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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204 views

Does attenuation to RF waves increases with frequency?

I heard somewhere that RF waves at high frequency such as above 2GHz face more attenuation while passing through air, buildings and due to humidity as compared to 800Mhz and 2) Waves at 30-40GHz ...
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51 views

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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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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183 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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455 views

Why does wavelength decide the size/diameter of these holes in the microwave door?

I've read here that microwaves are blocked by the holes in a microwave window because the holes on the door are small enough to prevent the microwaves from passing through. However, if wavelength is ...
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32 views

Time Domain Reflectometer

How can I analyze the data time domain reflectometer measurement from this picture?
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3k views

Advantages/disadvantages of a cylindrical microwave oven cavity in comparison to a rectangular cavity

Why are rectangular cavities preferred for standard microwave ovens with a frequency of 2.45 Ghz? What is the reason that you can hardly find a circular cavity? What are the disadvantages of ...
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239 views

Electric fields with different frequencies, total intensity?

What happens when electric fields with different frequencies are combined? Is it possible to calculate the intensity of the total electric field? For a project, I need to simulate a brain treated ...
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404 views

Can I safely heat stainless steel 1-2 inch ball bearings in a consumer microwave? [closed]

I am looking to heat 1 or 2 inch stainless steel spherical ball bearings in a microwave. I would like the bearings to get to about 140 degrees F but not hotter. I have read that this should be fine as ...
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234 views

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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356 views

Light / TEM wave in a hollow waveguide

I'm cramming for my EMF exam, and a question came up: Light in free space is an example for a TEM wave, isn't it? (Maybe thats already my mistake) And we learned that in a hollow waveguide only TE ...
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144 views

I need to remove water from a system [closed]

I work in an industry and I need to remove water from a system. The scenario: There is a washer and a blower on a conveyor belt. The item being washed is plastic (not sure what type) and can't be ...
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104 views

Why can microwave (in microwave oven) heat the food but wifi can't? [duplicate]

As far as i know, microwave (used in microwave oven) and wifi all operate on the same frequency, but why microwave can heat the foods while wifi wave can't?
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104 views

Why do (most) metals cause problems in a microwave oven? Which metals (if any) don't? [duplicate]

Most of us have seen microwave ovens with metal racks or shelves, which challenges the common notion that you can't (safely) put metal in a microwave oven. What's going on here? Is it a matter of ...
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164 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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107 views

Dodging Microwaves [closed]

I'm not sure if I'm just being paranoid or not but I'd like some explanation as to whether my fears are justified or not. With a normal microwave oven you can usually end the cycle early by opening ...
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185 views

About blocking of microwaves

When a phone is inside microwave oven and if we call it using wifi the phone doesnt recive call as frequency of wifi is same as frequency of wave generated in oven as there is a mesh like thing which ...
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209 views

If halving signal strength is only a 3db drop, why can't cell phones be much lower powered?

My phone can receive a signal that's -90dBm. That's roughly one-billionth of a milliwatt. Cutting a signal's strength in half only drops the signal by 3dBm. Apart from slightly higher range, is there ...
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227 views

5G networks and health concerns

Are there any peer reviewed journals on 5G networks and health concerns? I know very well that 5G radiation is of low frequency and non-ionizing and some concerns are related to the power of the ...
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72 views

How do microwaves communicate with satellites?

If microwaves only penetrate up to a few cm of food in a household appliance before being absorbed and transferring energy to water molecules, than how are microwaves able to communicate through long ...
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512 views

Are there photographs taken in only the microwave spectrum?

I've seen many cameras and photographs of light in infrared, visible, and ultraviolet. And many photos of space in all areas of the EMS. Are there any photos of landscapes or architecture in microwave ...
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76 views

Understanding the principle of photo diode signal generation

I have two lasers, both illuminate on a photo diode, i'm not very sure what's physically going on in the photo diode. My understanding is the following: The electric fields of both lasers add up and ...
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406 views

X-rays / Gamma rays “oven” vs microwave oven

Let's imagine a seller scammed you and sold you a Gamma rays / X-rays "oven" instead of a common microwave oven. The power consumption would be the same as a common microwave oven, i.e. about 1 kW, ...
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How to melt sand with microwaves?

Is it possible to melt sand with microwaves? Which frequency should they have? The melting point of the sand is 1.700°C and the mass is not homogeneous: there are a lot of pores and the composition ...
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95 views

Why do we have to switch off mobile phones during flight in airplanes? [closed]

During take offs the flight attendant makes sure that mobile phones are switched off (or maybe turned in airplane mode), why is that necessary? (I suspect that there is something to do with physics ...
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Microwave Grilles

Bit of an applied physics question here, to do with microwave ovens and the grille in the door through which you can see. My understanding has been that the grille works because the waveform of the ...
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63 views

RF signal on wirebonds

I am curious to know how RF signal is transmitted through wirebonds. I thought that in microwave transmission lines, the energy was stored in electric and magnetic fields inside the dielectric ...
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41 views

How is millimetre wave generated and why it cannot go higher to terahertz frequency?

I have been trying to find out how millimetre wave (3 GHz to 300 GHz) signals are generated but didn't find much. And I knew for some reason this method cannot generate THz electromagnetic waves, that ...
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136 views

Question on Microwave Oven : [duplicate]

Energy of Electromagnetic Radiations is given by e=hc/λ. Implying shorter the wavelength more the energy. Cooking food requires energy. So why we cannot use Cosmic Rays with wavelength of about 0.01 ...