Time‐domain reciprocity theorems for electromagnetic fields in dispersive media

Abstract

Time-domain reciprocity theorems of the time-convolution and the time-correlation type for electromagnetic fields in linear, time-invariant, and locally reacting media are discussed. Inhomogeneous, anisotropic, and arbitrarily dispersive, both active and passive, media are included. The analysis is entirely carried out in space-time, without intermediate r•ourse to the frequency or the wave vector domain. The application to inverse source and inverse constituency (or inverse profiling) problems is briefly indicated.

Generalized Optical Theorem in the Time Domain

“…(2), (5), (8), (9), the result in Eq. (21) can be written in the following form which is consistent with a result derived earlier in [25], Eq. (29):…”

“…It is well known (see [25], Eq. (24), and [26]) that the following modified reciprocity theorem holds:…”

“…The plots of U and S e are, indeed, very similar, as expected. In another set of [1,25]. In these simulations we considered a lossless nonmagnetic scatterer having δ = 0.1 0 (in Fig.…”

Security Analysis of Random Access Schemes

“…1, the solid and dash line represent the main channel (between a remote and a host station) and wiretap channel (between a remote station and an eavesdropper), respectively. The host station periodically broadcasts a pilot signal and a remote station can estimate a uplink channel using the received pilot signal by channel reciprocity [4] and path loss . A remote station transmits a random access packet consisting of preamble sequence ( ) for duration .…”

“…With channel-adaptive random access, since a remote station can estimate uplink channel condition by measuring downlink channel condition by channel reciprocity [4], a remote station transmits a random access packet only when the channel gain is greater and equal to a pre-determined threshold. If the channel gain is less than the threshold, a remote station waits to transmit until the channel gain becomes greater or equal than the threshold.…”