Realization of broadband impedance matching networks for enhancing the performance of underwater surveillance systems

Abstract

In this work, we have designed and investigated three & five elements based two different types of broadband networks for matching the output impedance of power amplifier (50□) with the input impedance of underwater spherical transducer having usable frequency band of 5kHz to 30kHz with resonant frequency of 17kHzin order to enhance the transmit sensitivity of transducer over its entire frequency. Steps followed in sequence involve: 1)In water measurement of Transducer's Impedance Parameters as a function of frequency using Impedance Analyzer, 2) Transducer's modeling using Van Dyke Model, 3) Designing of three & five elements based broadband matching networks using smith chart, 4) Transducer's simulation with and without matching networks, 5) Fabrication of matching networks and its characterization. Results evidenced that impedance of the transducer with both types of broadband matching networks becomes nearly equal to 50□ which significantly enhanced Transmit Power Gain (TPG), reflection coefficient,-3dB bandwidth and TVR of the system over the entire frequency band of the transducer.-3dB bandwidth of the transducer was enhanced from 4.5kHz to 12kHz with matching networks. Maximum enhancement in the TVR level was observed to be equal to 12 dB re 1Pa/V at 1 m