Focusing waves at arbitrary locations in a ray-chaotic enclosure using time-reversed synthetic sonas

Abstract

Time reversal methods are widely used to achieve wave focusing in acoustics and electromagnetics. Past time reversal experiments typically require that a transmitter be initially present at the target focusing point, which limits the application of this technique. In this paper, we propose a method to focus waves at an arbitary location inside a complex enclosure using a numerically calculated wave excitation signal. We use a semi-classical ray algorithm to calculate the signal that would be received at a transceiver port resulting from the injection of a short pulse at the desired target location. The time-reversed version of this signal is then injected into the transceiver port and an approximate reconstruction of the short pulse is created at the target. The quaility of the pulse reconstruction is quantified in three different ways, and the values of these metrics are shown to be predicted by the statistics of the scattering-parameter |S21| 2 between the transceiver and target points in the enclosure over the bandwidth of the pulse. We experimentally demonstrate the method using a flat microwave billiard and quantify the reconstruction quality as a function of enclosure loss, port coupling and other considerations.

Wave scattering properties of multiple weakly coupled complex systems

“…The Dynamic Energy Analysis (DEA) method involves solving for the phase-space energy density on a gridded domain [35], and describes mean high-frequency wave energy distributions in all sub-systems [36,37]. The Random Coupling Model (RCM) determines the statistical properties of the impedance and scattering parameters for complex enclosures [38][39][40][41][42][43][44]. In contrast to the other above mentioned methods, the RCM generates both mean-field and statistical predictions, treats interference and utilizes a minimum of information, namely, the system coupling details and the enclosure loss parameter [45][46][47][48][49].…”

Path Encoding Pulse Compression for Obtaining Novel HPM with Ultrahigh Repetition Frequency

“…In the above simulation, a full-blown technology of timereverse is adopted for realizing pulse compression [18,19]. However, the time-reverse technology is not the necessary condition for compressing a long pulse to a narrow pulse.…”

Efficient Statistical Model for Predicting Electromagnetic Wave Distribution in Coupled Enclosures

“…In contrast to the above mentioned methods, the RCM is able to describe the full probability distribution functions (PDFs) for voltages and currents at ports. An exemplary application of RCM is the simulation of the fluctuating impedance matrix based on minimal system information, namely a single-cavity loss parameter α (to be defined) and several system-specific features [2,3,[43][44][45][46][47]. The system-specific features include the radiation information of the ports (both emitting and absorbing), as well as short orbits inside the cavity.…”