Communication system transmit information from one place to another place by means of electric energy. This paper describes the analysis and design of electronic circuits used in radio frequency communication systems covering the frequency range up through several hundred megahertz the actual frequency lit depends upon whether the circuit is realized with decree components or as an integrated circuit.
The electromagnetic waves that leave transmitting antenna arrive at the receiving antenna in one of the many waves. These include ground waves, sky waves, space waves, and via satellites. Ground waves travel along the ground and follow the terrain. Radio wave propagation is concerned with how radio signal generated by a transmitter moves to receiver located some distance away. As the portion of electromagnetic frequency spectrum that is used for broadband wireless communication extends from 300 MHz to 300 GHz. The frequency range covers over wavelength from 1m to 1mm. In these frequencies bands, radio waves are transmitted as space waves. That is, neither ground nor sky waves are used at these frequencies.
The simplest radio –propagation environmental is free space with no atmosphere and no solid object along the path between the transmitter and receiver. Such an environmental permits radio signals to travel in a line-of-sight manner and be received as direct waves. Unfortunately, this model is oversimplification of practical propagation environments where the radiated wave comes in contact with solid objects that produce changes in its amplitude, phase, and direction of propagation. Even in the absence of solid objects, the radio signals strength decreases as the probation distance increases. The medium over which the radio wave travels has significant festivity, which means that when the radio wave comes in contact with it, the amplitude of the wave diminishes the further it travels,
Since radio waves are propagated as space waves in the range of frequencies associated with fixed broadband wireless access communication, the remainder of this chapter will be composed of a direct wave, which travels in line-of-sight manner, and a ground-reflected wave.
Radio waves propagate in several ways, depending on the path geometry, frequency of the wave, and temporal variability of the medium. There are three fundamentals propagation mechanisms.
When a radio wave impinges on an object that is very large compared to its wavelength, it suffers a reflection. Such objects include the earth’s surface, buildings, walls and aircrafts. Assume that a radio wave is initially travelling through free space. If the reflecting objects has different electrical properties from free space, such as perfect dielectric, the wave is partially reflected and partially refracted. If the object is a perfect conductor, all the energy is reflected back into free space.
The following paper covers issues like transmitter, receiver, modem and channel spacing requirements. The focus of...