Browsing by Subject "Wide beamwidth"

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    ItemOpen Access
    Design of a wideband and bi-directional transducer for underwater communications
    (2007) Elmaslı, Işıl Ceren
    A two ceramic layer stacked transducer structure for short range underwater communications at high frequencies is studied in this work. The structure has a wide bandwidth of one octave and operates at 350 kHz center frequency. Transducer structure inherently has two electrical and two acoustic ports. Ceramic layers are matched to water load through quarter wavelength thick matching layers on each radiating face. Using electrical ports separately to compensate for the large acoustic length of the structure in water is also investigated. It is shown that the wide bandwidth operation can be maintained. The beamwidth of the structure is narrow due to end - fire effect of two back – to – back radiating elements.
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    ItemOpen Access
    The design of a wideband and widebeam piston transducer in a finite closed circular baffle
    (2008-06-07) Şahin, Z.; Köymen, Hayrettin
    The design of a high power piezoelectric underwater transducer operating at frequency range 40 kHz-80 kHz with acoustic power capability in excess of 250W is described. The transducer consists of two back-toback elements. Each element is formed by stacked PZT-4 ceramic rings, a matching and a steel backing layer, and placed in a finite rigid circular baffle. We investigate the dependence of bandwidth and beamwidth to the combination of piston and baffle radii, a and b, respectively. With ka of 2.45 (κ is the wave number) at resonance and a b/a ratio of 2, the transducer resonates at 60kHz with 67% bandwidth and has a beamwidth of 60° at each half space. We show that when two transducers are placed at right angles spatially and driven in parallel, we can obtain an omnidirectional beam pattern in the lower frequency band. The beam pattern exhibits two dips in each quadrant at the higher end of the frequency band, which are within 8 dB. We also investigated power handling capability of the transducer from thermal point of view using finite element analysis. The input impedance measurements agree well with the numerical results within the pass band.