Difference between "radio frequency alternating current" and " radio waves "

[aneesholv]

Difference between "radio frequency alternating current" and " radio waves "

What is the Difference between "radio frequency alternating current" and " radio waves " ?

 

[G4BCH]

Re: Difference between "radio frequency alternating current" and " radio waves "

Current flows in a conductor
Wave propogates through space
Peter

 

[chaitu_b99]

Re: Difference between "radio frequency alternating current" and " radio waves "

Then what about a wave that propagates in wave guide.....is the alternating current is taken as a reference to the wave....or they both are same ???????

 

[aneesholv]

Re: Difference between "radio frequency alternating current" and " radio waves "

Suppose my FM radio modulation frequency is 91.9MHz , Our exciter modulate the audio with this frequency from the circuit , Then our transmitter antenna radiate this frequency to the air. Then please tell me what is the difference between the output frequency of exciter (that is the frequency 91.9MHZ) and the output of the transmitter antenna ( that is also 91.9 MHz) . Is the frequency 91.9 MHz is a Electro magnetic radiation ?

Regards
Aneesh

 

[Mark W. Ingalls]

Re: Difference between "radio frequency alternating current" and " radio waves "

Then what about a wave that propagates in wave guide.....is the alternating current is taken as a reference to the wave....or they both are same ???????

The answer you seek is contained within Poynting's Theorem.

Some of us find several serial question marks annoying, fyi.

 

[jiripolivka]

Re: Difference between "radio frequency alternating current" and " radio waves "

The answer you seek is contained within Poynting's Theorem.

Some of us find several serial question marks annoying, fyi.

The frequency of a RF current or the electromagnetic wave in a space is a description of how fast the charges move. Frequency unit is Hertz, earlier it was "cycles per second".

In conductors and waveguiding structures, conductors and dielectrics are combined so when the RF current flows in conductive walls or charges move in dielectrics, RF power can be transmitted from one end to the other end of such "line".

One end of such line is then connected to a device called antenna, to facilitate the RF power transfer into space. Antennas generate the electromagnetic free-space wave; close to the antenna, the wave has a spherical wavefront; farther from it we call such wave a planar wave. Its wavefront is a plane perpendicular (or normal) to the line of propagation. In this plane (moving along the propagation line by the speed of light [in vacuum]), the electrical and magnetic components alternate so that they are mutually orthogonal. This holds for the linear polarization; if the wave propagates with a circular (or elliptical) polarization, the E and H components are turning around the line of propagation, again staying orthogonal.

As you can see, there are many details: please find a textbook and read it carefully. Antennas by J.D.Kraus is one of the best; if you wish to understand electromagnetism without too much of math, try ARRL Radio Amateur's Handbook, issued annually by ARRL.