Analysis of a Thin Circular Loop Antenna Over a Homogeneous Earth

It is well known that a high altitude nuclear burst generates an intense electromagnetic transient which covers a large geographical area.1 This transient field induces currents in communication circuits and, if these are large enough, adversely affects communication channels. One problem of particular interest in land-line communication is the coupling to large loops formed by cables. The loops formed by cables deployed in practical communication systems are very complex and cannot be analyzed easily. Typically, they run for many miles over inhomogeneous terrain and contain many junction points; nevertheless a great deal of insight into the behavior of these irregular loops can be obtained by studying the behavior of a large regular loop over a homogeneous ground. In this paper, the theoretical foundations for an analysis of a circular loop over a homogeneous ground are developed, for time harmonic excitations. The 1215 1216 T H E BELL SYSTEM TECHNICAL JOURNAL, J U L Y - A U G U S T 1970