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