All Questions
Tagged with antennas microwaves
10
questions
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
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
vote
1
answer
24
views
Can lenses and mirrors be described in terms of beamwidth and directivity?
As a first background, I am an Electrical Engineer with experience in antennae design for microwave bands.
Lately, I have been interested by optical devices, and I notice one strange phenomenon: when ...
- 117
5
votes
2
answers
3k
views
How come a mobile phone signal is blocked by aluminium foil, but Wi-Fi gets through?
Major puzzle for me. I have done a demonstration in lectures for years now, where I show that a mobile phone call can be blocked by wrapping the phone in a single sheet of standard Aluminium kitchen ...
- 133k
0
votes
1
answer
27
views
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 ...
- 1
0
votes
1
answer
45
views
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 ...
- 311
0
votes
2
answers
507
views
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 ...
- 111
0
votes
2
answers
2k
views
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 ...
- 1,123
13
votes
1
answer
296
views
Why is it that fractal antennas can filter out so many frequencies?
As known, fractal antennas are used for example in cell phones. But why is it that so many different kinds of frequencies can be filtered out of the forest of radio waves surrounding us? Is it because ...
1
vote
0
answers
120
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 ...
- 235