Exploring Antenna Limits: Frequency and Current in Wireless Devices

In summary, the conversation discusses the limits of frequency and current that can be transmitted by a wireless device. It is stated that there are no limits, but there are practical limits that need to be considered. The size of the antenna and its efficiency play a role in determining the limits, and coiling the antenna can increase its resistance to change in current. Additionally, the frequency of the receiving circuit and the size of its capacitance can also affect the limits. Ultimately, the limits are determined by budget and practicality.
  • #1
mtanti
172
0
I have a weird question I think... I'de like to know how low a frequency and how high a current can a wireless device transmit.

eg, radio frequency is over 1000s of Hz, can it be much lower than that?When you receive a radio signal to an antenna, a small current is generated which is interpreted as sound. How high can that current be?

If there's no limit to the amperage generated at the receiving end, how can you calculate it?
10x!
 
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  • #2
well, just check the electromagnetic spectrum chart, somewhere higher or lower, it won't be a radio signal anymore.
 
  • #3
It's not a weird question at all.

There are no limits. But there are practical limits. For example, if you start
off by saying that you have a 1 MegaWatt transmitter, then you can determine
how large your antenna has to be if you fix the frequency in order to achieve
a certain efficiency.

You can make a 0.00001 Hz tansmitter and deliver billions of amps through
the antenna. Just not on the Earth because the planet is too small to hold the
antenna.
 
  • #4
re

low frequency antenna don't have to be a long piece of wire, you can have large coil of wire that when unwound is just as long.
 
  • #5
waht said:
low frequency antenna don't have to be a long piece of wire, you can have large coil of wire that when unwound is just as long.

I'm not an electrical engineer, so this is partly a question. It seems to me that coiling the antenna would give it a higher inductance, and therefore a higher resistance to change in current. Doesn't that limit the amplitude of the signal you can transmit/receive?

Also, I was thinking about the frequency of the receiving circuit. From what I've heard, you "tune" to a specific frequency by creating a circuit that has a natural frequency at that of the desired radiation, creating a resonance. Might there be practical limits to the natural frequency of this circuit? How large can one make a capacitance in practice?
 
  • #6
The area of the coil would have to go up in order for it to be an efficienct radiator.
The number of turns won't make it more effieicient but it would change the way
you would drive the antenna. Look up "Radiation Resistance" to discover how.

The practical limit on capacitance is set by your budget. Bill Gates could
afford many many Farads.
 

What are antenna limits?

Antenna limits refer to the maximum performance capabilities and restrictions of an antenna.

What factors affect antenna limits?

The size, shape, and material of an antenna can affect its limits, as well as environmental factors like weather and interference from other devices.

How do antenna limits impact signal range?

The limits of an antenna can determine the maximum distance at which it can transmit and receive signals effectively.

What are the consequences of exceeding antenna limits?

Exceeding antenna limits can result in reduced performance, interference with other devices, and potential damage to the antenna.

How can antenna limits be improved?

Antenna limits can be improved by optimizing the design and materials of the antenna, as well as using signal amplifiers or signal boosters.

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