Antenna and Wave Propagation textbook by Bakshi pdf free download. In wireless communication systems, signals are radiated in space as an electromagnetic wave by using a receiving transmitting antenna and a fraction of this radiated power is intercepted by using a receiving antenna. Drajver hdmi dlya noutbuka asus. Thus, an antenna is a device used for radiating or receiver radio waves. An antenna can also be thought of as a transitional structure between free space and a guiding device (such as transmission line or waveguide). Usually antennas are metallic structures, but dielectric antennas are also used now a day., In our discussion we shall consider only metallic antennas.

Here we shall restrict our discussion to some very commonly used antenna structures. Some of the most commonly used antenna structures are shown.

Time-varying currents radiate electromagnetic waves. A time varying current generates time-varying electric and magnetic fields. When such fields exist, power is generated and propagated.

Antennas And Wave Propagation, G. Raju, Pearson. Frequency planning, Free space loss, Fresnel zone clearance bending of radio beam.

Although theoretically any structure carrying time varying current can radiate electromagnetic waves, all structures are not equally efficient in doing that. While in many applications we try to reduce the radiation, when radiation is intended, the launching of waves into space is accomplished with the aid of specially designed structures called antennas. If the time varying current density established on an antenna structure is unknown, the radiated fields can be calculated without great difficulty.

A more difficult problem is determination of current density J on an antenna such that the resultant field will satisfy the required boundary conditions on the antenna surface.