Active cloaking with wideband transducers
AssigneeImage Acoustics, Inc.
InventorJohn L. Butler
Life of this patent
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Abstract
Electro-mechanical transducers are used to actively cloak a targeted object in a way that absorbs incoming waves without reflection, sends them out the opposite side of the target and returns the wave without leaving a shadow behind the target. The present invention pertains to an improvement in the cloaking of an object without requiring the use of special materials for the object itself and allows the use of SONAR and other possible transducer systems that would be covered and rendered ineffective with passive cloaking materials. Other means are also provided for extending the bandwidth as well as increasing the efficiency for cloaking or other transducers.
Claims19
An electro-acoustic cloaking transducer system including transducer means, said targeted object having front and rear object ends to provide an acoustic transduction cloak on or about the targeted object so that incoming sound appears to pass through the targeted object without reflecting sound from the targeted object and also leaving no acoustic shadow so as to thus appear acoustically invisible, said transducer means comprising at least one pair of transducers including front and rear transducers that are positioned on the respective front and rear object ends of the targeted object and circuit means disposed on the targeted object and inter-coupling the front and rear transducers, said front transducer positioned to absorb an impinging wave front substantially without reflections and said rear transducer positioned for re-transmitting the wave front at the rear side, said circuit means comprising electrical wiring connected between the front and rear transducers providing bi-directional signal transmission between the front and rear transducers.
An acoustic cloaking transducer system including transducer means, said targeted object having front and rear object ends to provide an acoustic transduction cloak on or about the targeted object so that incoming sound appears to pass through the targeted object without reflecting sound from the targeted object and also leaving no acoustic shadow so as to thus appear acoustically invisible, said transducer means comprising at least one pair of transducers including front and rear transducers that are positioned on the respective front and rear object ends of the targeted object and circuit means disposed on the targeted object and inter-coupling the front and rear transducers, said front transducer positioned to absorb an impinging wave front substantially without reflections and said rear transducer positioned for re-transmitting the wave front at the rear side, further including shunt inductances and clamped capacitances with the shunt inductances able to tune out the clamped capacitances allowing the mechanical resonance frequency of the transducer to be lowered by means of a series electrical inductance which adds an effective mechanical mass to the actual mechanical masses or raise the resonance frequency by means of series electrical capacitance which adds an effective mechanical stiffness to the actual effective mechanical stiffness.
An acoustic cloaking transducer system including transducer means, said targeted object having front and rear object ends to provide an acoustic transduction cloak on or about the targeted object so that incoming sound appears to pass through the targeted object without reflecting sound from the targeted object and also leaving no acoustic shadow so as to thus appear acoustically invisible, said transducer means comprising at least one pair of transducers including front and rear transducers that are positioned on the respective front and rear object ends of the targeted object and circuit means disposed on the targeted object and inter-coupling the front and rear transducers, said front transducer positioned to absorb an impinging wave front substantially without reflections and said rear transducer positioned for re-transmitting the wave front at the rear side, and further including negative impedance converters to increase the bandwidth and efficiency of the transducers by adding a negative clamped capacitance in shunt with the actual clamped capacitance and by adding a negative version of the mechanical impedance of the transducer, without the radiation resistance, in electrical series with the transducer to cancel the mechanical impedance of the transducer but not the radiation resistance.
Dependencies are inferred from the claim text.