The modal projectora)
Three modal projector beam patters with weighting factors: (a) A 1 = 1, A 2 = 0; (b) A 1 = 1, A 2 = 0.414; and (c) A 1 = 1.6, A 2 = 0.8.
Monopole, dipole, and quadrupole modes with corresponding beam patterns.
Voltage distribution from weighted contributions of each stack for the voltages of monopole, dipole, and quadrupole modes with dipole shading value 0.4.
Distributed parameter equivalent circuit for an element of the modal projector.
Calculated circuit model and measured TVR results for the monopole, dipole, and quadrupole modes of a five ring modal projector array.
Photo of an end view of one ring and a fully assembled eight-ring PZT-8 driven modal projector.
Eight-ring array measured (a) and finite element (b) narrow cardioid TVR with weightings A 1 = 1.6 and A 2 = 0.8.
Measured omni (–––), dipole (- - -), and quadrupole (• • •) mode beam patterns: (a) below resonance at f 0, (b) resonance at 1.2f 0, and (c) above resonance at 1.4f 0.
Measured ring array resultant narrow cardioid beam patterns with weightings A 1 = 1.6 and A 2 = 0.8: (a) below resonance at f 0, (b) resonance at 1.2f 0, and (c) above resonance at 1.4f 0.
Single crystal two-ring array measured, equivalent circuit, and finite element model TVR.
Flux lines for the modal projector Terfenol-D stacks.
Photo of an end view and fully assembled two-ring Terfenol-D driven modal projector.
Measured SPL response in the monopole (omni) and narrow cardioid modes for the Terfenol-D modal projector for 4 and 1 W input, respectively.
Modal beam characteristics from Eq. ((3)).
Single crystal modal projector characteristics.
Gain in level for the narrow cardioid mode for 1 W input.
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