TABLE OF CONTENTS K.D. Baker and D.A. Burt
Department of Electrical Engineering
Utah State University, Logan, Utah
In dc and low-frequency circuits, the elements of resistance, inductance, and capacitance are treated as lumped-circuit elements. In reality, the parameters of wires and other elements are distributed over some volume, and at higher frequencies, their distributed characteristics become more and more important. Distributed parameters are probably one of the largest contributors to the discrepancies between drawing-board design and actual performance of working equipment. For this reason, this chapter is devoted primarily to showing the magnitude of these parameters and some examples of the troubles that can occur because of them.
Dc resistance is the best known and most thoroughly tabulated electrical parameter of materials. The formula for the resistance of a body of uniform cross-sectional area is simply
| (36.1) |  |
where <i class="emphasis">R</i>=resistance, <span class="unicode">?</span><i class="emphasis"> <span class="unicode">?</span></i>=volume resistivity of the material<i class="emphasis"> l</i>=length of the conductor<i class="emphasis"> A</i>=cross-sectional area of the conductor
The values of ? for many materials have been tabulated in reference books and hence will not be duplicated here.
The resistivity of all materials is a function of temperature. In general, the resistance of semiconductors and insulators will decrease with increasing temperature, whereas the resistance of most metals will increase with increasing temperatures. As an example, the resistivity...
