Analysis of electromagnetic (or acoustic) multipath propagation inventively focuses upon the transmitter-to-target propagation (transmitted propagation reaching target via both direct pathway and forward scattered pathway) and the target-to-receiver propagation (re-transmitted propagation reaching receiver via both direct pathway and forward scattered pathway). Transmitter-to-target propagation is calculated using conventional multipath modeling technique. The target's overall scattered field is calculated using the calculated transmitter-to-target propagation in conjunction with qualitative electromagnetic/acoustic target information. Target-to-receiver propagation is calculated using conventional multipath modeling technique and/or the reciprocity principle as applied to the calculated transmitter-to-target propagation. Jointly disclosed (practicable therewith or thereapart) is inventive confinement of the assessment of multipath propagation to a "surface interactive region" ("SIR"), intermediate the target and transmitter and/or the target and receiver. The down range time of the propagation, translatable to range distance, is related to error associated with such restriction. A SIR scope is selected commensurately with acceptable error.