Research on dual-band impedance matching method of acoustic transducer while drilling based on an improved particle...

Conventional logging-while-drilling tools require two distinct transducer arrays to achieve monopole and quadrupole mode logging. This paper proposes a dual-frequency impedance matching network design methodology that enables a single transducer array to efficiently generate high-fidelity outputs for both monopole and quadrupole modes simultaneously. The approach is grounded in the multi-mode equivalent circuit model of the transducer. A compression factor is incorporated into the model to enhance convergence characteristics, and an improved particle swarm optimization algorithm is employed to precisely calculate the component parameters of the dual-frequency impedance matching network. After adding the dual-frequency impedance-matching network, the transducer can achieve good active power output simultaneously in monopole mode and quadrupole mode. The operating frequency band is broadened by 1.5 times, and the active power is enhanced by 1.9 times. At the representative frequencies of 4.5 and 14 kHz, the transmitting voltage response is enhanced by 21% and 12%, respectively. Impedance matching yields a 32.34 dB improvement in the maximum horizontal directivity for the monopole mode and a 43.18 dB improvement for the quadrupole mode, while simultaneously enabling mode-specific filtering that attenuates excitation signal peaks. The hydrophone test results show that after impedance matching, the excitation signal's main energy is more concentrated and significantly enhanced. This dual-frequency impedance-matching network can effectively enhance the energy output of the acoustic logging tool emission system while drilling, improve the tool's signal-to-noise ratio, and provide a reference for research on high-performance detection instruments.