A discussion and survey of model-based parameter estimation in computational electromagnetics

Most EM phenomena, whether observed in the time domain or the frequency domain, or as a function of angle or spatial location, are not of interest at one or a few discrete times, frequencies, angles or locations but, instead, require essentially continuous representation over some specified observation interval. Even with increasingly sophisticated instrumentation and computer models now available, determining EM observables to sufficient resolution as a function of the relevant observation variable can be expensive as well as potentially error-prone. A typical problem now involves determining time- or frequency-domain responses over bandwidths that are no longer just a few percent or a few megahertz, but might extend over frequency ranges that are 10:1 or more in relative bandwidth or multiple gigahertz bandwidths in absolute terms. Resolving a response that contains many high-Q, closely spaced resonances requires slow sweeping rates or long observation times experimentally, or an excessive number of frequency samples or time steps computationally. Similar observations can be made about angle and space responses. This paper describes a procedure for circumventing such problems.