Hello guys hello everyone. I would like to know how the antenna or aerial as it called, works!! I searched many websites about this theme but vain effort! There is not any website that explain exactly how this aerial (any type) works! I know some basic information that aerial works with electromagnetic waves and and sometimes analog signal, (or digital signal?). But I know also that if something should work it needs neg and pos cable. The aerial work with one cable. This does not make sense. How its possible?

 

How its possible?

The ground (planet Earth) is the second "cable".

 

You don't need the earth or ground to transmit an electromagnetic wave. All you need is accelerating charge, space and the fact that change across space is not instant (there is a universal speed limit). Usually the electrons in the antenna provide the source of charge(s) that are accelerated by a rapidly changing potential across space so you have a difference in potential (a voltage/electric field) across space that causes the charge(s) to move in response (a current/magnetic field) like you would see in a circuit. So unlike a typical DC or low frequency AC circuit where the EM energy is constrained near the conductors, in the antenna the EM circuit is the universe.

http://www.edn.com/design/sensors/4...ds-and-antenna-radiation-takes-almost-no-math

 

OK....... I confused!!!

 

Hello,

A lot of information on antennas and their theory can be found in the links of the following page:
http://ac6v.com/antprojects.htm

Bertus

 

Aaaaaaaa this is the way on how it works!! Thanks guys and you too bertus

 

You can read and study for years to find your answers. And still be puzzled.

An antenna is an open inductor, open capacitor circuit. The circuit is charged with EM......but can't discharge back into the circuit. So it discharges the EM into space.

The exact dynamics are debatable.

Enjoy.

 

Wow I didn't knew that! Thanks bro!

 

Yes but how it determined on the circuits, (give a simple circuit, so as to be able to understand your theory). What exactly makes the antenna work? The capacitor, the inductor, the resistor, the diode, the transistor? The electromagnetic waves cannot be generated from their self! Something creates them (I know the motion of electrons generate them, but this electromagnetic waves is way too low) a component that I don't know!

 

You can't start big with these concepts. If we explain it, you wouldn't understand how the parts work together.

These concepts have to be understood from the bottom and in order.

When I was first learning, we only had textbooks. You have all the information in the world on the internet.

Start reading. Pages in order. When you don't understand something....ask a question. They have textbooks on this site.

Your first question will not be how to built an oscillator. It will be how much current is flowing.

The better you understand the basics......the less questions you will have later and the more you will figure out on your own.

In case the internet goes down.

 

OK thank for the tip

 

Yes but how it determined on the circuits, (give a simple circuit, so as to be able to understand your theory). What exactly makes the antenna work? The capacitor, the inductor, the resistor, the diode, the transistor? The electromagnetic waves cannot be generated from their self! Something creates them (I know the motion of electrons generate them, but this electromagnetic waves is way too low) a component that I don't know!

That a big point that you are probably missing -- a changing electric field induces a changing magnetic field, while a changing magnetic field induces a changing electric field. So not only can an electromagnetic wave generate an electromagnetic wave, that is how they propagate through space. If you crank the math, you will discover that a requirement for this to happen is for the wave to propagate at the speed of light (in that medium).

 

It sounds like there is a lot of drama where the OP lives!

 

I would like to know how the antenna or aerial as it called, works!!

I didn't know this name so I took a look on Google and I found that this is the typical TV antenna.

However, If you are fine with EM theory, you might look up at basic dipole analysis and antenna's arrays & coupling. Take a look at Yagi Uda type as well.
A very well complete reference is the Orfanidis book

http://www.ece.rutgers.edu/~orfanidi/ewa/

which covers electromagnetic waves and antennas theory.
There is a lot to study

 

This is a good simulation of a Yagi Uda antenna that shows the near to far field changes in EM field patterns.

In the video you can see the radiation fields moving away from the antenna and the reactive near/Ex/Ey fields moving near the antenna conductors but then dissipate into space exponentially as they interact with moving radiation fields. As the EM field moves from the source the phase of the E and H fields wave peaks change from ~90 degrees out of phase reactive energy in near field at the antenna to in-phase real energy in the far field wave-front. How quickly this happens depends on the type of antenna. Electromagnetically short antennas with large reactive near fields are best for extending this effect. This phase change over space can be used to calculate the distance from a HF emitter with a fairly long wavelength by separate field measurement of the electric and magnetic phase changes at different points in space near the (possibly hidden ) transmitter.

https://en.wikipedia.org/wiki/Near-field_electromagnetic_ranging

 

That a big point that you are probably missing -- a changing electric field induces a changing magnetic field, while a changing magnetic field induces a changing electric field. So not only can an electromagnetic wave generate an electromagnetic wave, that is how they propagate through space. If you crank the math, you will discover that a requirement for this to happen is for the wave to propagate at the speed of light (in that medium).

There's nothing which could be able to reach the speed of light!! The speed of light is equal to:
c=U/t where U=speed of the measured mass and t=time in seconds. We know that the light can reach from the sun to the earth in 8 minutes. In this case we have:
If light can reach in 480 (8 mins) the length sun/earth in 150000000 Km
Then in 1 second ------------------------------------------------------------------- X

=480*X=150000000*1
=480*X=150000000
X=150000000/480
X=312500 Km/second (300000Km/sec)

Now for the electromagnetic waves it can reach at 295700 km/sec (almost a speed of light) but it's OK!
That how brain works

But the only thing I cannot understand it is how the antenna (I mean R/C antenna) export electromagnetic waves by just one cable! This in some words is...is impossible! The antenna needs a GND! It looks like you mean that the light bulb can lights if we connect just one cable of the battery! The light bulb will not lights up if there will not a gnd cable! It's impossible! But if there is something that I'm wrong I need explanation! I have read so much books for the radio antenna and electromagnetic waves, I didn't found a book that explains how the antenna works! All the books says that the antennas transmit and receive electromagnetic waves and some formulas! But there is not any book that says how this antenna works! With which way it works? What power make the antenna transmit waves? I need the piece on the antenna theory! Nicola Tesla did not make antennas circuits based on the logic that the antenna can transmit and receive waves! He found that some kind of power or something like that makes the antenna take out the radio waves on the space! That is thing that I wanna know! I know that antenna transmit and receive! That knows and my grandmother too!! But I want to know what is this power that turns an impossible to possible! Take out the radio waves to the space!

 

There's nothing which could be able to reach the speed of light!! The speed of light is equal to:
c=U/t where U=speed of the measured mass and t=time in seconds. We know that the light can reach from the sun to the earth in 8 minutes. In this case we have:
If light can reach in 480 (8 mins) the length sun/earth in 150000000 Km
Then in 1 second ------------------------------------------------------------------- X

=480*X=150000000*1
=480*X=150000000
X=150000000/480
X=312500 Km/second (300000Km/sec)

Now for the electromagnetic waves it can reach at 295700 km/sec (almost a speed of light) but it's OK!
That how brain works

But the only thing I cannot understand it is how the antenna (I mean R/C antenna) export electromagnetic waves by just one cable! This in some words is...is impossible! The antenna needs a GND! It looks like you mean that the light bulb can lights if we connect just one cable of the battery! The light bulb will not lights up if there will not a gnd cable! It's impossible! But if there is something that I'm wrong I need explanation! I have read so much books for the radio antenna and electromagnetic waves, I didn't found a book that explains how the antenna works! All the books says that the antennas transmit and receive electromagnetic waves and some formulas! But there is not any book that says how this antenna works! With which way it works? What power make the antenna transmit waves? I need the piece on the antenna theory! Nicola Tesla did not make antennas circuits based on the logic that the antenna can transmit and receive waves! He found that some kind of power or something like that makes the antenna take out the radio waves on the space! That is thing that I wanna know! I know that antenna transmit and receive! That knows and my grandmother too!! But I want to know what is this power that turns an impossible to possible! Take out the radio waves to the space!

So what you are claiming is that light can't travel at the speed of light.

 

That is thing that I wanna know! I know that antenna transmit and receive! That knows and my grandmother too!! But I want to know what is this power that turns an impossible to possible! Take out the radio waves to the space!

There is only one solution for that. Education.

Your idea of how circuits operate is limited by your mental picture of how electrical energy moves in a circuit (it's not in the wires or electrons usually). I've been a proponent of a more fields based approach to electronics and circuits for a long time just because of these types of conceptual problems.
http://amasci.com/elect/poynt/poynt.html

 

So what you are claiming is that light can't travel at the speed of light.

The light is the faster thing in universe in technical ways! The light can reach that speed 300000Km/sec. The electromagnetic waves cannot reach that speed!! Only in vacuum and I'm not sure for that! In vacuum it can reach as I said 296700 km/s almost a speed of light. But the light is faster as known the speed of light!!

 

It's not about power. It's about conversion. We are converting an angular EM field into a linear EM field.