[SOLVED] Why power is used to transmit signals through an antenna (not voltage or current)

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Hello

I have a very basic question, but the answer is not explained in RF textbooks.

When we use an antenna, we care about the transmitted and received 'power', not voltage or current.

Even in antenna matching circuits, we care about 'power'.

What is the reason?
 

As electric magentic wave, olny E or H can not exist.
Both E and H must be exist at same time.

Consider Poynting vector, ExH.

Impedance is determined by voltage and current.
 
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CHL said:
When we use an antenna, we care about the transmitted and received 'power', not voltage or current... What is the reason?
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Consider the antenna as a load; it dissipates the energy (takes in and pushes out the other side) fed into it.

Electromagnetic radiation is associated with energy- not voltage or current. If either the voltage or the current is zero, no power (energy /time) will be radiated.
 
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if you have a voltage across a resistive load (a receiving antenna), you also have power. I do not see the difference you are speaking of
 

CHL said:
Hello
.............

When we use an antenna, we care about the transmitted and received 'power', not voltage or current.
.................

What is the reason?
Click to expand...

Do you understand what Power (Watts) is ? it equals volts x amps :wink:



biff44 said:
if you have a voltage across a resistive load (a receiving antenna), you also have power. I do not see the difference you are speaking of
Click to expand...

indeed, likewise,
I think he? just hasn't quite put it all together yet ( the basics)


Dave
 

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