A lower bound to the broad-band power scattered from an electrically linear antenna with a general lumped load

A mode analysis that is independent of detailed field expression is made of the total power P_sc(ω) scattered from an electrically linear body of arbitrary size and shape, excited by a single-frequency incident field and loaded at a reference port. This load may be linear, nonlinear, and passive, or nonlinear and active at a given frequency ω. P_sc(ω) is the sum of a scatter mode power that is proportional to the scatter-mode radiation resistance, a transmitter mode power that is proportional to the port radiation resistance, and their cross power. The form of this expression for P_sc yields criteria for determining whether an antenna could be a minimum-scattering (MS) Dicke antenna, an MS antenna as defined by W.K. Kahn and H. Kurss (1965), or a CMS antenna of the type of W.K. Kahn and W. Wasylkiwskyj (1966). The general expression for P_sc(ω) yields a load-independent lower bound. An expression analogous to P_sc for the bistatic power P_sc(ω) scattered into a specified solid angle is presented. A lower bound to P_sc(ω) is obtained. Its integral frequency yields the broadband lower bound