engleski

General Theory and Practice of Basic Models in The Building of Hydroacoustical Antennas

In this paper in first part of work is presented a model of vibration of medium with concentrated mechanical parameters as a starting point of analyses of receive sensitivity of hydroacoustical transducer. Mathematical solution of its differential equation is carried out on the basis of Laplace transformation of complex variable. On the basis of its mathematical solutions we have analyses of frequency characteristic of receive sensitivity of hydrophone. The results of complex solution is graphically shown in two important fields: the field of exponential rise value and field of constant value of elongation of material point with field of resonance and field of quickly fall of value of sensitivity. In accordance with the complete behavior of function of elongation of concentrated mass in dependence of frequency with damping in resonance we have real figure of receive sensitivity as a very important parameter of hydroacoustical transducer. In a second part of this paper is presented the new procedure of calculating of different characteris-tics of a hydroacoustical antenna. The procedure is derived on an idealized model of a block scheme of hydroacoustical transducer. In hydroacoustical system with one piezoelectric element (hydro-phone), the value of a phase angle on the electrical clamp comes from phase relations in mechanical vibration in electromechanical vibration systems of single elements and has not great importance and influence on other parameters of simple model. But, on the other hand, the values of a phase angle with too great dispersion of different parameters at receive multi-element antennas, can has negative influence on the parameters which are very important for great ranges of sonars and medi-cine ultrasound scanners, too. The subject of this third part of work are presented two groups of equations of electrical matching of hydroacoustic piezoelectric transducers, by means of an electrical transformer and a LC transformer, to the wave resistance of an antenna electric cable, which is connected to transceiver sonar. Given analyses of antenna with concentrated mechanical parameters are in accordance with mathematical solutions by two port network model of hydroacoustical transducer with original concentrated elec-tric parameters and with the electric substitute of mechanical parameters inside the body, at electrical clamp on one side and on the surface of the transducer in the water on the second acoustical side. With the analysis of the behavior of mathematical functions of hydroacoustical sensitivity and sources of wide dispersion of phase angle of impedance of antenna elements at hydroacoustical and ultrasound transducers, we can choose the best model for optimal matching in the given sonar sys-tem. By using the ideal electric transformer models, special, original and general expressions were gained and tested in the long-time practice, we have enabled the correct computing of elements nec-essary for performance and the complete matching of impedance at hydroacoustical antenna. In accordance with the mentioned intentions of presenting fundamental sensitivities of transducers, electroacoustical impedance and their matching, we have presented a new important expanded and correct opinion about the fundamentals of directivity pattern of acoustic energy in maritime volume zone, directivity index and effective aperture of antenna in a new form of absolutely correct mathe-matical functions dependent on important parameter Level of Suppression of Side-lobes – LoSoS. Also, all of them in two and three dimensional graphs are the best support in the building of anten-nas and new technologies of contemporary systems of monitoring for a world without accidents in space and, especially, in the underwater. Accordingly, with analyses of behavior of mathematical functions of sensitivity and sources of great dispersion of sound or electro-magnetic energy of antennas elements at hydroacoustical/ultrasound or radio antennas, we can choose the best model for optimal range in given system.

elongation of material point ; hydrophone ; dispersion of phase angles, concentrated mechanical vibration system of single elements, hydroacoustical transducer, multi-elemental antenna, electrical impedance matching, ideal electrical transformer model, LC transformer, wave resistance of electric cable ; piezoelectric hydroacoustic transducer ; sonar

U radu su dane izvorne matematičke formule najvažnije parametre složenih hidroakustičkih pretvarača i antena s grafičkima prikazima funkcija ponašanja. Jedinstvene matematičke formule za indeks usmjerenosti i efektivnu površinu izvedene u hidroakustici važe i u jednadžbama radilokacije u radarskoj tehnici i radioastronomiji u potpunosti.