- The invention of television or a succession of discoveries
- The discoveries that introduced the invention of television
- The birth of the term "television"
- From the mechanical television (1925-1931) to the electric television (1932-1945)
- Television in the footsteps of players like the radio
- The FCC and Congress: state control
- The networks: diffusion
- U.S. companies: financing
- Television and the American public
- Television proved to the Americans
- The placing of television sets on the market
Electromagnetic phenomena are integral part of our life they happen in phones, wireless networks, radios, televisions and satellite channels. Electrical signals are sent in the form of electromagnetic waves in order to diffuse a lot of information. The biggest problem for the users of these appliances is to capture them correctly. When we are in a no-coverage zone, our parabola is misguided and our television displays 'snow', this is often due to the poor reception of signals.
We have used this logic to develop our TPE. We decided to use a wireless radio to test the reception of radio waves.
We will try to determine how to alter the reception by a radio receiver of a radio wave. First, we will explain the structure of a radio wave, its formation and the functions of a radio. Then we will see the propagation of waves in space. Finally, we will explore the different ways to create interference between radio waves emitted by a normal radio station and those emitted by another source.
All observations in this part is in an isotropic space which is linear and homogeneous. An Isotropic space is a space where there is an invariance of properties of the medium depending on the direction of the propagation of radio waves. It must be linear and homogeneous, so we did not change the properties of the medium.
The electromagnetic field:
Consider a wire carrying a sinusoidal alternating current, all wires that carry a current driver creates a magnetic field around it. On the axis of the coil, the magnetic field H is perpendicular to the plane of the coil. Also, this wire carries an alternating current. An electric field E is caused by the potential difference between the two strands of thread. Its field lines that are distributed in planes intersecting with the dipole are on the line of intersection. These are the very fast changes of the alternating current that allow the propagation of electromagnetic field.
Resonance: Resonance is a phenomenon that is essential for the functioning of a radio. Resonance is the increase in energy when an oscillating frequency of the excitation frequency is close to the normal system of vibration. The oscillating energy for an electronic circuit is the increase in the intensity of the alternating current.
So, when two circuits are excited at the same frequency, there is a transfer of energy between these two circuits.
An LC circuit is a circuit that consists of a coil and a capacitor. A coil is a dipole that is composed of one or more turns of a wire around an axis. A capacitor is an electric dipole that is capable of storing a charge in a circuit.
As we saw earlier, radio waves propagate in space in directions that are determined by the shape of the antenna.
The permeability of the waves against a Faraday cage:
The radio was embedded in aluminum foil, so that the antenna does not touch the aluminum. It was found that the radio did not emit sounds that were understandable