Decomposition of the moment method impedance matrix into quasi-static and residual components (dipole antennas)

By extending the concept of separating the Green's function into singular and nonsingular parts to an additive decomposition of the impedance matrix, three matrices, namely, a static elastance matrix which alone determines the static charge; a static inductance matrix which, combined with the elastance matrix determines reactive behavior below resonance; and a residual frequency-dependent matrix are obtained. Using the quasistatic solution and a first-order approximation for the residual matrix, the authors obtain an equivalent circuit valid up to about one-half of the resonant frequency. It is concluded that for electrically small antennas, where radiation bandwidth is limited, this technique offers a novel method to determine circuit limitations. This approach extends the quasistatic theory of distributed circuits to the realm of practical computation. >