Determining of directivity index and effective aperture at the idealized model of directivity pattern of antenna with elliptical cross section of main lobe.

In this paper a new universal procedure of calculating directivity index (directivity factor) and effective aperture dependent on the measured directivity pattern of antenna will be presented. The procedure derives from an idealized model of directivity pattern measured characteristics of a sonar antenna in accordance with the elliptical cross section perpendicular to acoustic axes of the main lattice of directivity pattern. My new, strong, and original condition for very low level of suppression of side lobes at the contemporary sonars (LoSoSMiZ condition <−50 dB), its meaning in directivity index and effective aperture on ranges at previous congresses, and its meaning in theory of reverberation are in accordance with this theory too. In accordance with the equations in this paper, the de-embedding of directivity indices and effective aperture of the receive antennas of sonar systems is simple, fast, reliable, accurate, and widely usable. Finally, the de-embedding of directivity index and effective aperture according to the conditions in this paper makes a better evaluation of given parameters possible: for buyers, in R&D, in academies, and on the operative levels.