Acoustic transducer with trapezoidal, irregularly pitched, or widened transducer elements

An apparatus comprising:

• a downhole acoustic measurement tool comprising a transducer, wherein:
• the transducer is operable for emitting and/or receiving acoustic signals to perform downhole measurements;
• the transducer comprises a plurality of piezoelectric elements;
• and
• the piezoelectric elements are irregularly pitched azimuthally around one or more portions of a circumference of the transducer.

An apparatus comprising:

• a downhole acoustic measurement tool comprising a transducer, wherein:
• the transducer is operable for emitting and/or receiving acoustic signals to perform downhole measurements;
• and
• the transducer comprises a plurality of piezoelectric elements spaced apart by no more than the distance defined by W1*f1/FUL, where FUL is the upper limit of the frequency band of interest, W1 is the width of the transducer interelement spacing that produces parasitic mode at frequency f1.