Questions tagged [radiation]

While rare, this tag should be used for questions pertaining to using electronic devices (passive or active) in an ionizing radiation environment. This could be space, medical facilities or physics labs. Defense or military related questions are probably classified.

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Why are there two different charges on a patch antenna? How are these charge distributions formed?

If we apply an AC signal to a capacitor, we can see only one type of charge on an individual plate. If we apply an AC signal to a patch antenna, there are two different charge distributions on the ...
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Is the ground plane in patch antenna used as a reflector? If so, how does the distance between ground plane and patch affect the reflected signals?

For a reflector to work it should be placed quarter wavelength away from the source so that waves reflected back from the ground plane are in phase with the waves being generated and superimpose. In ...
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1 answer
58 views

Why are patch antennas used instead of planar dipole antennas?

As far as I know, the major advantage of patch antenna over dipole antenna is its directivity. If the planar dipole antenna can achieve the same directivity then why do we use patch antennas? Are ...
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3 votes
1 answer
245 views

How does selecting a higher permittivity substrate in patch antenna reduce its size?

By selecting a higher permittivity substrate do we reduce the height of the antenna or we reduce the length of the patch antenna? We cannot reduce the length of the antenna as it is dependent on the ...
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1 vote
1 answer
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IR LED Safety: Subtend Angle and Retinal Exposure Limit

The relevant formulas from OSRAM AN090 "Eye safety of IREDs used in lamp applications" with slight modifications : $$ Z = (l + w)/2 $$ $$ \alpha = Z/d $$ $$ L_{ir} \approx \frac{I_e R(\...
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2 answers
69 views

Can a LC circuit generate frequencies in the Gigahertz range or higher?

For instance, if you took a bunch of off the shelf capacitors and arranged them in series and a bunch of inductors and arranged them in parallel, could you make the resonant frequency of the LC ...
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1 answer
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Does a DC power supply 24V 6A that functions as a motor for a standing desk produce radiation that might be harmful?

Just curious to know if there's any radiation coming from it that can be harmful if we stay close. Thanks.
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Microwave Turntable Absorption

Do microwaves turntables absorb some microwave radiation when being used? I heard that they can act as a minimum load on the magnetron. If this is true, can I interchange microwave turntables? Edit: ...
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2 votes
1 answer
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How do I find out the dimensions of a rectangular waveguide given the frequency I want to operate it at?

I want to design a horn antenna to detect the 21 cm hydrogen line. I know how to optimize the antenna dimensions by taking into account some functions that approximate the phase errors and ...
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2 votes
0 answers
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Why have space-grade components such long leads? [duplicate]

What are the reasons why (some) space-grade components are shaped like they are, with their characteristic long flat leads, golden finish, etc.? Image: DP83561-SP from TI Are the assembly houses ...
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Antenna radiation plot and negative gain values

In general, how to interpret the negative gain values on antenna radiation diagram plot? I have attached an example. My guess is that they represent some value relative to some reference value. If so, ...
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1 vote
2 answers
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How to increase efficiency of antenna without moving antenna far from tree?

I have designed a monopole antenna at 868MHz frequency. Now I would like to attach that antenna to the tree (wood). But, due to Why does placing an antenna far from the wood increase the efficiency of ...
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Why does placing an antenna far from the wood increase the efficiency of the antenna?

I designed a monopole antenna at 868MHz frequency. I placed wood as the surrounding material. I noticed that placing the antenna far from the wood increases the efficiency of the antenna. Can anyone ...
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Is it possible to create a device that can decode the EM waves generated from an electronic machine?

I recently watched a movie in which the hero (a robber) invents a device that can capture and decode the EM waves generated from an Automated Teller Machine (ATM) during its use. The movie claims that ...
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4 answers
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FCC testing for boards with programmable firmware

I'm curious how FCC conformity testing is done on PCBs that contain devices with programmable firmware. Specifically, boards that are designed to allow the end-user to reprogram the firmware (such as ...
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1 vote
2 answers
104 views

What are up-screened components?

What are up-screened components/devices in the frame of qualification of electronic components? How is it done?
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2 answers
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Calculating loss due to emission of EM waves (AC)

In AC due to the fact that electrons are accelerated back and forth they emit electromagnetic radiation. Electromagnetic radiation must depend on the value of AC because more accelerated charges emit ...
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1 answer
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finding the side lobe level of an antenna array

I have a circular antenna array with N elements, for which the array factor can be defined as follows: $$AF(\phi)=\sum_{n=1}^N I_n \cdot e^{j \cdot(kr \ cdot \cos(\phi-phi_n)+\beta_n}$$ I search a lot,...
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1 answer
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Derivation of Dolph-Taylor Synthesis

Today, I was trying to deduce by myself the Dolph-Taylor Synthesis. After arriving at the expression: $$AF(\theta) = P_{N-1} \left( \cos \left( \frac{\psi}{2} \right) \right) = T_{N-1} \left(x_o \cos \...
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How to determine radiation at a certain distance from a sunlamp

I have a sunlamp, with four UV bulbs, emitting UVA and UVB. These are parallel-mounted tube bulbs and the total area of the light emitting area is 20 cm × 25 cm = 0.05 m2. Each bulb is 15 W and so ...
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0 votes
1 answer
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Removing collected charges in a IC CMOS circuit exposed under a 30keV electron beam source

I would like to know if there is any mechanism (for example UV light exposition) to remove charges collected in an IC CMOS circuit that was exposed under a 30keV electron beam source. Presumably, ...
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-1 votes
1 answer
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400Mhz frequence HackRF One

All, Sorry but I am new to this topic and have no experience with SDR myself.First, I briefly give the hardware that I am using: HackRF One Following antenna: https://zsecurity.org/product/atheros-...
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0 votes
1 answer
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How can someone determine from the surface current distribution the electric field polarization?

How someone can determine by looking at the surface current direction what e-field components to expect? For example only \$E_\theta\$ or only \$E_\phi\$ ?
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With Bluetooth turned off in PC settings, do keyboards and mice still emit radiation? [closed]

Do you know if a wireless mouse emits radiation in wired mode? Using the USB cable, With Bluetooth turned off, but with the switch set to "On"? And also do you know if a wireless keyboard, ...
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Where are the sensors of the EMF/RF meter on the circuit board?

In the attached photo you can see the PCB of a simple EMF/RF meter. This meter shows, at the same time, the values of the electric field, magnetic field, and power density (see small illustration on ...
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1 answer
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What is relation between power deposition and frequency?

1. What is relation between power deposition and frequency in electromagnetic waves? 2. Is it true that even very low power elec.mag.waves can be "dangerous" for long time health if ...
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Maximum Allowed Radiated Continous Wave Power in 61.25GHz ISM Band

I am looking into a possibility for 60GHz energy harvesting for low power sensor nodes and I am little confused about the differences I have found between the US and European regulations related to ...
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2 answers
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How 3mG can be dangerous if the Earth's magnetic field is 500mG? [closed]

All the things I have read says that magnetic fields above 3milligauss is dangerous for people. How this can be true if the Earth has a magnetic field of 500mG? Do smartphones and gaussmeters measure ...
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1 vote
0 answers
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temperamental LED light

I have installed LED tubes in my kitchen ceiling light. They replaced the old fluorescent tubes. I removed the ballast and wired the fixtures according to instructions which essentially connected the ...
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1 answer
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Replacing X-ray or any radiation generating vacuum tubes with solid-state alternatives? [duplicate]

What are the reasons X-ray vacuum tubes could not be replaced by solid state alternatives? I'm thinking if it is possible to make a compact solid-state X-ray or higher energy photons generator just ...
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Do the bremsstrahlung radiation size depends on the size of the accelerator?

According to https://apps.dtic.mil/dtic/tr/fulltext/u2/a351472.pdf HERMES III, a 16 terawatt pulsed power accelerator at Sandia National Labs, which fired electron beams with peak energy at 22 MeV and ...
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-4 votes
1 answer
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60 GHz radiation

I have always gotten great answers on this site so I thought I'd give this one a shot. In looking into 5G technology, I found that it radiates at 60 GHz, which apparently is in the oxygen absorption ...
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3 answers
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How does being exposed to strong radiations effect nanosatellite electronics equipment?

I'm on paper designing a nanosatellite power system. The satellite would be orbiting in LEO. And I am wondering how and what type of radiation would affect its electronics. The system has a ...
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2 votes
2 answers
224 views

Burn hazard of IR LED Array Question

I am performing eye safety calculations on a device and I have hit a roadblock. To perform the calculations I have been following the IEC 62471 "Photobiological safety of lamps and lamp systems&...
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0 votes
3 answers
208 views

Thermal resistance in vacuum

Is it possible to obtain an approximate guess of what the thermal resistance of a device (i.e. a power MOSFET) would be in a vacuum based on the ambient thermal resistance value provided in the ...
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1 answer
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Steel cooker is not a Faraday cage? [closed]

I read that steel/iron/metal/conducting cages, with gaps less than the wavelength of electro magnetic waves, shield whatever is inside from that radiation. But when I put my mobile inside a cooker and ...
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0 answers
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Plotting the radiation pattern of a dipole antenna using MATLAB

I want to plot the radiation pattern of a half wavelength dipole antenna using MATLAB. But in dB scale, the plot has undesired peaks. The code is shown below: ...
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0 votes
3 answers
161 views

How can I prevent microwave radiation absorption by a camera lens/electronics inside the microwave (behind the shield)?

Let's say I put in an endoscope like camera with the lens at the inside edge of the box and the wire behind metal sheet. Here's a mockup: Possible idea: The lens is behind a holes but the hole is ...
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-1 votes
2 answers
102 views

What kind of camera could work inside a microwave?

I want to record video inside a microwave, is it possible? What if it was hid behind a shield or the same galvanized material as the door? The detailed structure may completely ruin visibility tho
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0 votes
2 answers
41 views

Direction of the main beam of an antenna

How can I find direction of the main beam of an antenna if antenna has radiation intensity as following? $$U=[\dfrac{sin(5\pi cos\theta)}{10sin(\pi cos(\theta/2))}]^2$$ Where $$0<\theta<\pi$$ My ...
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0 votes
0 answers
28 views

Side lobe level of an aperture antenna

There is a electric field in the far zone of the rectangular aperture antenna as shown below. Antenna lies along the xy plane. $$E_{\theta}=\dfrac{jke^{-jkr}}{4\pi r}\dfrac{sin(0.5\lambda k sin\theta ...
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-3 votes
1 answer
76 views

Practicality of Faraday door [closed]

Building a Faraday bed enclosure..wanted to ask which style of door would you advise in terms of seal - hinge,magnetic,Velcro etc. Measurements of the door is 900*900
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14 votes
4 answers
5k views

Are there any advantages to using rigid RF coaxial cables?

While watching this Signal Path video, I came across this shot: I saw few rigid coaxial cables there and so I started wondering what might their advantages be. I could only find disadvantages: They'...
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-1 votes
1 answer
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Can ESP32 radiation cause health hazards?

I am using ESP32 chips for a smart health monitoring device. I will use WiFi 802.11n or Bluetooth BLE/EDR depending on the amount of data to be transferred, so the unit will be mounted on hand, maybe ...
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0 answers
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Question regarding GM Tubes Calibration Frequency

My friend has has been using GM Tubes for more than a decade now. He has been calibrating them once per year. But the calibration data reveals that his GM Tubes would have remained within allowed ...
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1 vote
1 answer
88 views

What does these heatsinks do?

I think sharing the video will be the easiest way of describing the situation. The transistors are electrically isolated from the heatsinks, I have checked with multimeter. Few days ago, I have ...
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-3 votes
1 answer
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How to block / lessen EM-radiation/signal from home Wi-Fi router? [closed]

1) What materials and how can I use to completely block radiation from two antennas of my WiFi router? 2) What materials and how can I lessen by 20-50% radiation/signal from the third router antenna? ...
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-2 votes
2 answers
221 views

How much electromagnetic/electric radiation does laptop/computer emit? [closed]

How much electromagnetic or electric radiation does laptop emit? I don't know in what measurement system you have to answer, but at least, I want to get the answer which should be enough "research" ...
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Interpretation of data

I hope this question meets the standards of this platform, if not please inform me of how I can improve it. I was trying to design an antenna and I have done so. I am planning on using this antenna ...
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0 votes
0 answers
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Increase in gain of CP micro-strip patch antenna [duplicate]

I have successfully designed my circularly polarized patch antenna shown below. I used the slot method. Which as a bandwidth of 23MHz and a resonance frequency of 915MHz. Though the bandwidth is small ...
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