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. 2019 Jul 22;6(5):921–928. doi: 10.1093/nsr/nwz085

Figure 2.

Figure 2.

PPM capable of propagating directional waves. (A) Pressure distribution at six positions of the porpoise's biosonar surface. (B) The corresponding distribution of the PPM device. (C) Acoustic wave propagation of the omni-directional system without PPM, where a short pulse at a central frequency of 30 kHz was used; the snapshots correspond to the propagation times at 0.5 ms, 0.7 ms, 0.9 ms, respectively. (D) Propagation plots of the biosonar model, where the main beam angle and −3 dB beam width were estimated as 52° and 24°, respectively. (E) Propagation plots of the PPM device, where the main beam angle and −3 dB beam width were estimated as 58° and 18°, respectively.