Re fl ections In the previous section it was stated that the forward and backward waves may be entirely unrelated and of different shapes. This situation may be brought about if quite independent excitations are applied at both the source and the load of the line. More commonly, however, some exc...
Relation of voltage to current So far we have pictured simply the voltage on the line, but that voltage is of course accompanied by a current. We now ask what relation this current has to the voltage. To find the relation between voltage and current, we substitute v back in equation 2.6 and inte...
Saturated ferromagnet In a dielectric medium the individual atoms may or may not have permanent dipole moments. When an electric field is supplied, atoms initially without a dipole moment may acquire one with a strength proportional to the ele...
Scalar quantities Much of the time in this course we will be dealing with variables which directly express the values of the physical quantities, such as, for example, voltage or current. If those physical quantities have a time variation, so do the variables of our equations. In such a case, wh...
Solution of the equations We note that the equation above gives two values for γ, of which one must be in the first quadrant, and the other in the third. We denote the value in the first quadrant by γ, and its real and imaginary parts by α and β. The value in the third quadrant is called −γ. It...
Source and vortex fi elds In our study of electric and magnetic fields we will be greatly aided by the concepts of sources and vortices, originally developed, as the names suggest, in the study of fluid dynamics. The concepts themselves will be e...
Sources of Loss In a disipative medium the sources of loss we may encounter are dielectric loss, magnetic hysteresis loss, and conduction loss. We present here a treatment of the mechanism of conduction loss; the other forms of loss may be treated in a manner which leads to similar results macro...
Special cases again The input admittance of a transmission line for various special cases of termination at the load end is shown in Table 2.3 Case Admittance Open circuit load YI = jY0 tan βl Open Circuit λ/4 Line YI →∞ i.e. s/c Short circui...
Stokes theorem When a vector field intersects a non-closed surface S bounded by a contour C as shown in Figure 1.7, and the sense of the contour is chosen so that it is related to the sense of the surface area by the right hand rule, it has been shown by Stokes that Notice that the line integral...
Surface currents A surface current can be regarded as the limiting case when a finite amount of current I flows as shown in Figure 6.2 in a thin slab of area dimensions a and b and thickness t While t is small but not zero we may describe this situation in terms of a volume current density J or ...
