All Questions
Tagged with electromagnetic-radiation antennas
221
questions
-4
votes
2
answers
82
views
Can we catch signals from a cellphone using an external device? [closed]
What if someone stole em waves from our mobile devices to listen to our conversations or get our OTP. Whatever encryptions they have they are just EM waves innit and they cannot be propagated only in ...
1
vote
0
answers
42
views
Dipole antennas and the $B$ field
A dipole antenna responds to the electric component of a EM wave. Does the magnetic component of a EM wave have any effect on the performance of a receiving dipole antenna?
- 55
15
votes
7
answers
2k
views
Why does the length of an antenna matter when electromagnetic waves propagate perpendicular to the antenna?
The optimum length for a dipole antenna is a multiple of half the wavelength that it is designed to receive or emit. Why is this? If an electromagnetic wave has E in the x-axis, B in the y-axis, and ...
- 161
139
votes
2
answers
71k
views
How many photons are received per bit transmitted from Voyager 1?
As of 2024, according to https://voyager.jpl.nasa.gov/ , Voyager 1 is around one light·day away from Earth and still in radio contact. When Voyager 1 sends messages to Earth, roughly how many photons ...
- 7,012
1
vote
2
answers
97
views
Electromagnetic field of dipole antenna
Why do dipole antennas generate EM waves by alternating electric fields instead of alternating magnetic fields?
Why don't alternating magnetic poles detach the magnetic field like how it can do so ...
- 156
1
vote
2
answers
52
views
Minimum frequency for a dipole antenna to work
Does a dipole antenna need a minimum frequency of AC to make the electric field detach and propagate?
- 156
3
votes
0
answers
64
views
Can cell phones send message in the elevator?
From Gauss's theorem, a closed, hollow conductor shields its interior from fields due to charges outside, but does not shield its exterior from the fields due to charges placed inside it. So my ...
- 267
1
vote
1
answer
55
views
Understanding radiation mechanism of inset fed microstrip antenna
I have designed a simple inset-fed microstrip antenna, resonating at 2.45 GHz.
The transmission line model of the antenna reduces it to two radiating slots separated by a microstrip line, and it's ...
0
votes
0
answers
60
views
Effective aperture as a function of Azimuth and Elevation Angle
Wikipedia says
The effective aperture of an antenna is given by $$A_{\mathrm{e}}(\theta, \phi)=\eta A \cos \theta \cos \phi ,$$
where, $(\theta, \phi)$ are the azimuth and elevation angles relative to ...
- 101
1
vote
0
answers
54
views
How to practically generate longitudinal waves in a plasma
It can be read almost everywhere that plasma is the best convertor of transverse waves to longitudinal waves.
I'm not much interested in the theory here. Rather, I would like to know how to do it in a ...
- 487
-1
votes
1
answer
93
views
How does an antenna work?
I'm looking for a model of an antenna that would explain how it works an in particular where the values of impedance like 36.5 ohms come from. I've tried looking but everything i found was overly ...
- 31
2
votes
4
answers
166
views
Dipole Antenna: Electromagnetic Wave
I have read about wave propagation and dipole antennas here. I do not understand how a single electromagnetic wave (i.e. the electric field in particular - I can come up with the magnetic field later) ...
0
votes
1
answer
149
views
Wave Propagation: Dipole Antenna
I was watching the following video here. This video explains the following image below represents an electric field generated from a dipole antenna. How does a single wave of electromagnetic radiation ...
1
vote
2
answers
88
views
Which theory/model explains electrons movement inside a transmitting antenna? [closed]
I have an understanding of electrical circuits, however I am very interested to know more about electromagnetic waves radiation.
In particular I want to know how an oscillating voltage causes the ...
-1
votes
2
answers
72
views
From the physics standpoint, how should I align a USB Internet stick relative to the nearest cell tower in order to have the best signal? [closed]
I use this USB Internet stick:
(Huawei E3372h-153)
To connect to the Internet, I simply insert a SIM card into this stick and then insert the stick into a USB port of my laptop.
Based on my ...
- 1,599