单个圆形活塞换能器指向性

%Title：半径为R的圆形活塞换能器指向性函数（研究声波频率的影响，半径R固定50mm） %D(θ,φ,w)=|2 (J1 (kR sin?θ ))/(kR sin?θ )| %参数设定 %声波频率f，决定k f1 = 500; %声波频率500Hz f2 = 1000; f3 = 2000; f4 = 4000; v = 340; %声速340m/s numda1 = v / f1; k1 = 2 * pi / numda1; numda2 = v / f2; k2 = 2 * pi / numda2; numda3 = v / f3; k3 = 2 * pi / numda3; numda4 = v / f4; k4 = 2 * pi / numda4; %半径R参数 R = 0.05; %圆形活塞换能器半径50mm %偏角Theta n = 200; Theta = linspace(-pi/2, pi/2, n); Z1 = k1 * R * sin(Theta); y1 = 2 * abs(besselj(1, Z1) ./ Z1); Z2 = k2 * R * sin(Theta); y2 = 2 * abs(besselj(1, Z2) ./ Z2); Z3 = k3 * R * sin(Theta); y3 = 2 * abs(besselj(1, Z3) ./ Z3); Z4 = k4 * R * sin(Theta); y4 = 2 * abs(besselj(1, Z4) ./ Z4); plot(Theta*180/pi, y1, Theta*180/pi, y2, Theta*180/pi, y3, Theta*180/pi, y4); title('圆形活塞换能器指向性随声波频率f变化图(R=50mm)','Fontsize',30,'Color','b'); axis([-90, 90, 0, 1.1]); text(-80,0.95,'f=500Hz','FontSize',18); %指定坐标处进行标注 text(-60,0.9,'f=1KHz','FontSize',18); text(-40,0.85,'f=2KHz','FontSize',18); text(-20,0.8,'f=4KHz','FontSize',18); grid on; xlabel('角度'); ylabel('指向性'); legend('f=500Hz', 'f=1KHz', 'f=2KHz', 'f=4KHz'); %图例标注右上角