But the sound field generated by this kind of transducers in medium has s ome " congenital " shortcomings : there always exist zero areas in sound - axes of near - field however we change the frequencies and radii of transducers , so we need to look for better radiate transducers . in this dissertation , we design and make two kinds of radiate transducers : bunchiness control transducer with electric polarity division and gaussian transducer 然而，这种类型的换能器在媒质中产生的辐射声场，有其“先天性”的不足之处，在近场中无论平面活塞的频率和半径如何变化，轴上和沿径向上都呈现出极大和极小交替分布的干涉现象，因此我们有必要继续寻求更为理想的辐射形式。
