Contents
What is far field radiation?
The far field is the region in which the field acts as “normal” electromagnetic radiation. In this region, it is dominated by electric or magnetic fields with electric dipole characteristics.
What is meant by spherical wave?
[′sfir·ə·kəl ′wāv] (physics) A wave whose equiphase surfaces form a family of concentric spheres; the direction of travel is always perpendicular to the surfaces of the spheres.
Are all waves spherical?
Most waves are well-modeled as spherical, cylindrical, or plane waves. Plane waves (having planar phasefronts) are of particular importance due to wide applicability of the “locally planar” approximation.
What are the far field conditions for an antenna?
The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna.
What determines intensity of radiation?
Radiation intensity is defined as the power per unit solid angle, that is the power incident on that portion of the surface of a sphere which subtends an angle of one radian at the centre of the sphere in both the horizontal and the vertical planes.
What is a field region?
It’s a region immediately surrounding the antenna where the reactive field predominates. The electric and magnetic fields are not necessarily in phase to each other and the angular field distribution is highly dependent upon the distance and direction from the antenna.
What is spherical wave example?
One common example of a spherical wave is a sound wave. When an object oscillates or vibrates in the presence of medium, a sound wave is produced and this wave propagates outward in all possible directions. As the wave travels outward, it carries energy.
How is a spherical wave formed?
The energy of the wave moves in a direction perpendicular to the wave front. There are three types of wavefronts. a) Spherical wave front: A spherical wave front is produced by a point source of light. This is because all the points equal distance from a line source lie on the surface of a cylinder.
Is sound a spherical wave?
Spherical Wave (Sound) This is the wave produced by an elementary point source. This wave propagates isotropically – that is, the wave amplitude is spherically symmetric.
Which antenna is used in aircraft?
UHF antennas are commonly used for transponders and distance measuring equipment (DME), and they are always found on the bottom of the aircraft. They are about four inches long, and the same antenna can be used for both systems because the transponder frequency is in the middle of the DME frequency band.
What is a reactive field?
The reactive near field is the region where the fields are reactive i.e the E and H fields are out of phase by 90 degrees to each other. For propagating or radiating fields, the fields must be orthogonal to each other but in phase.
Which factor is not dependent on the intensity of radiation?
The stopping potential, work function of the surface and maximum kinetic energy of photoelectrons do not depend upon the intensity of light used. Only photocurrent depends.