Home Antenna Systems Reflection References
An electromagnetic wave
is composed of an *electric field and a **magnetic field and travels
through space at the speed of light.
Electric fields and magnetic fields are produced in all electric circuits and the energy in those fields is usually (and intentionally) returned or contained in the circuit. Energy that is not returned to the originating circuit is radiated or released. In electrical circuits, radiated energy is usually undesired. One reason for this is because the radiated energy adversely affects electrical components and circuits by presenting EMI, or electromagnetic interference. Another reason to prevent radiated energy is to minimize lost energy to achieve maximum efficiency.
In a "radio" transmitter, electromagnetic radiation is exactly what is desired. This radiation must be transferred completely because reflection of energy back to the transmitter circuit can causes higher than desired power in the transmitter components.
*An electric field is the electric force per unit charge.
**A magnetic field is produced by flow of electric current and is the force on a moving charge. This current flow can be in a wire, in the orbit of an electron, or in the movement of charge through a magnet.
Electric fields and magnetic fields are produced in all electric circuits and the energy in those fields is usually (and intentionally) returned or contained in the circuit. Energy that is not returned to the originating circuit is radiated or released. In electrical circuits, radiated energy is usually undesired. One reason for this is because the radiated energy adversely affects electrical components and circuits by presenting EMI, or electromagnetic interference. Another reason to prevent radiated energy is to minimize lost energy to achieve maximum efficiency.
In a "radio" transmitter, electromagnetic radiation is exactly what is desired. This radiation must be transferred completely because reflection of energy back to the transmitter circuit can causes higher than desired power in the transmitter components.
*An electric field is the electric force per unit charge.
**A magnetic field is produced by flow of electric current and is the force on a moving charge. This current flow can be in a wire, in the orbit of an electron, or in the movement of charge through a magnet.