On possibility of the antenna array pitch extending of narrow sector-scanning sonars thanks to axial shift of even or add elements in half the pitch
Abstract
On possibility of the antenna array pitch extending of narrow sector-scanning sonars thanks to axial shift of even or add elements in half the pitch
Incoming article date: 04.06.2020This article deals with the hydrophone antenna arrays (the results of studying are applicable to radio-frequency aerials as well) the elements of which are connected in parallel on one coordinate (in the columns). The mathematical models had been developed which were derived from the formula of the directional characteristic of a right-angled flat radiator embedded into the absolutely hard baffle. A level of overshoots of the directional characteristic (as related to a principal maximum) amounts approximately 0.3; a coefficient of decreasing overshoots of the directional characteristics because of shifting lines is approximately equal to 1.4 for the array (8 x 8 or 16 x 16) with a pitch equal to wave length, with shifting lines to half the array pitch, a gap between the elements is 0.1 of the array pitch and a direction of beams is not more than 15 degrees on both sides with respect to the normal to an antenna plane. Without the gap between the elements at the abovementioned conditions the overshoots and the coefficient of their decreasing will be approximately equal to 0.2 and 1.6 respectively. Thanks to extending the antenna array pitch a number of antenna elements is being reduced, and consequently, a number of the receiving channels and power amplifiers will be reduced as well. The simulation results are presented including computed two-dimensional directional characteristics of the antennae. The overshoot dependences upon beam direction and antenna array element dimension are also shown.
Keywords: antenna, element, array, array pitch, element pitch, directional characteristic, side-lobe level, narrow sector of scanning, increasing of array pitch