Transducer receiving voltage inputs, such as square waves, rich in harmonics

Abstract

A transducer member is made from a piezoelectric material (e.g. barium titanium) having a looped configuration and a gap in the loop and having properties of vibrating upon the introduction of an electrical voltage to the transducer member. A support member made from steel or aluminum and having a looped configuration and enveloping, and attached to, the transducer member has a gap aligned with the transducer member tap and has properties of vibrating with the transducer member. The transducer member may have a uniform thickness around its periphery or a progressively increasing thickness with progressive distances from the gap. The transducer has a high mechanical Q (e.g. 8-12) and a particular resonant frequency when disposed in air or in a vacuum. When the transducer is disposed below the earth's surface, its resonant frequency may vary because of variations in the earth's characteristics at the different positions. An alternating voltage having the particular frequency as its fundamental frequency is applied to the transducer member with a particular amplitude. The voltage has harmonics with large amplitudes (as in a squarewave) relative to the particular amplitude. When the transducer member is disposed in the earth, sound pressure waves are produced in the transducer with larger amplitudes at harmonics and overtones of the fundamental frequency over a wide frequency range than the magnitude of the amplitude at the fundamental frequency. The harmonics and overtures produce an enhanced recovery of the oil from the earth regardless of the earth's variable characteristics.