ok BSc PhD CEng MIEE Vodafone Ltd. RV Goodman CEng MIEE Broadcasting and Telecommunications Engineering Consultant Contents Principles 6/3 Generation of the electromagnetic wave 6/7 Reception of the electromagnetic wave 6/12 The space wave 6/13 The sky wave 6/20 The surface wave 6/22 References 6/25 This page intentionally left blank Principles 6/3 6.1 Principles Equally E could have been eliminated, to give Equation 6.10. 6.1.1 Fundamental laws of electromagnetism (6.10) Many engineering aspects of propagation do not need a knowledge of the historically derived principles, but these do provide a good If E or H is disturbed at a point within a homogeneous non-con- background. The fundamental laws of electromagnetism are: ductive medium, a 'wave' is produced which propagates away from the point with a velocity V metres/sec. When this disturbance is a 1. Gauss' electrostatic theorem: the normal component of electric sinusoidal oscillation of frequency Hertz, the wave equations may displacement (flux) D, integrated over any closed surface be solved for a general wave front of any shape, by considering it to equals the total charge p within the surface. be composed of a set of plane waves. One of these plane waves can 2. Gauss' magnetic theorem: the normal component of magnetic be expressed in a cartesian frame, such that it progresses along the induction B, integrated over any closed surface is zero. Z axis with electric field along the Y axis. Then it has a solution, at 3. Faraday's law of electromagnetic induction: the parallel com- time t, proportional to expression 6.11, where B is 2 divided by the ponent of electric field E, integrated round a closed path is wavelength in metres. proportional to the rate of change of the flux of magnetic induction enclosed by the path (Lenz's law: the constant of ,-j(z-vr) (6.11) proportionality is minus one). 4. Ampere's law for magnetomotive force: the parallel component of magnetic field H, integrated round any loop equals the total Analysis shows that this plane wave has it