simulation of antenna radiation pattern-horn

EX NO 8

Antenna radiation pattern-Horn

AIM To simulate horn antenna radiation pattern using MATLAB APPARATUS REQUIRED MATLAB software, PC SOURCE CODE function []=horn; disp('E-Plane and H-Plane Horn Specifications'); %R1=[]; R2=[]; %R1 = input('rho1(in wavelengths) = '); %R2 = input('rho2(in wavelengths) = '); R1=6; R2=6;a=0.5; b=0.25; a1=5.5; b1=2.75; %a=[]; b=[]; %a = input('a(in wavelengths) = '); %b = input('b(in wavelengths) = '); %a1=[]; b1=[]; %a1 = input('a1(in wavelengths) = '); %b1 = input('b1(in wavelengths) = '); u = (1/sqrt(2))*((sqrt(R2)/a1)+(a1/sqrt(R2))); v = (1/sqrt(2))*((sqrt(R2)/a1)-(a1/sqrt(R2))); u = Fresnel(u); v = Fresnel(v); w = Fresnel(b1/sqrt(2*R1)); DH = 4*pi*b*R2/a1*((real(u)-real(v))^2 + (imag(u)-imag(v))^2); DE = 64*a*R1/(pi*b1)*((real(w))^2 + (imag(w))^2); DP = pi/(32*a*b)*DE*DH; k = 2*pi; Emax = 0; Hmax = 0; % E and H plane Outputs % E-Plane Amplitude for(theta = 0:0.5:360); I = theta*2 + 1; theta = theta*pi/180; phi = pi/2; ky = k*sin(theta); kxp = pi/a1; kxdp = -pi/a1; t1 = sqrt(1/(pi*k*R1))*(-k*b1/2-ky*R1); t2 = sqrt(1/(pi*k*R1))*(k*b1/2-ky*R1); t1p = sqrt(1/(pi*k*R2))*(-k*a1/2-pi/a1*R2); t2p = sqrt(1/(pi*k*R2))*(k*a1/2-pi/a1*R2); t1dp = -t2p; t2dp = -t1p; I1 =.5*sqrt(pi*R2/k)*(exp(j*R2/(2*k)*kxp^2)*(Fresnel(t2p)-Fresnel(t1p)) + exp(j*R2/(2*k)*kxdp^2)*(Fresnel(t2dp) - Fresnel(t1dp))); I2 = sqrt(pi*R1/k) * exp(j*R1/(2*k)*ky^2) * (Fresnel(t2) - Fresnel(t1)); y(I) = (1 + cos(theta))*I1*I2; y(I) = abs(y(I)); end for(I = 1:721)

if(y(I) > Emax) Emax = y(I); end end for(I = 1:721) if(y(I) <= 0) Edb = -100; else Edb = 20*log10(abs(y(I))/Emax); end theta = (I-1)/2; x(I)=theta; q1(I)=Edb; end % H-Plane Amplitude for(theta = 0:0.5:360); I = theta*2 + 1; theta = theta*pi/180; phi = 0; kxp = k*sin(theta) + pi/a1; kxdp = k*sin(theta) - pi/a1; t1 = sqrt(1/(pi*k*R1))*(-k*b1/2); t2 = sqrt(1/(pi*k*R1))*(k*b1/2); t1p = sqrt(1/(pi*k*R2))*(-k*a1/2-kxp*R2); t2p = sqrt(1/(pi*k*R2))*(k*a1/2-kxp*R2); t1dp = sqrt(1/(pi*k*R2))*(-k*a1/2-kxdp*R2); t2dp = sqrt(1/(pi*k*R2))*(k*a1/2-kxdp*R2); I1 = .5*sqrt(pi*R2/k)*(exp(j*R2/(2*k)*kxp^2)*(Fresnel(t2p)-Fresnel(t1p)) + exp(j*R2/(2*k)*kxdp^2)*(Fresnel(t2dp) - Fresnel(t1dp))); I2 = sqrt(pi*R1/k) * exp(j*R1/(2*k)*ky^2) * (Fresnel(t2) - Fresnel(t1)); y(I) = (1 + cos(theta))*I1*I2; y(I) = abs(y(I)); end for(I = 1:721) if(y(I) > Hmax) Hmax = y(I); end end for(I = 1:721) if(y(I) <= 0) Hdb = -100; else Hdb = 20*log10(abs(y(I))/Hmax); end theta = (I-1)/2; x(I)=theta; q2(I)=Hdb; end % Figure 1 ha=plot(x,q1); set(ha,'linestyle','-','linewidth',2); hold on; hb=plot(x,q2,'r--'); set(hb,'linewidth',2); xlabel('Theta (degrees)'); ylabel('Field Pattern (dB)'); title('Horn Analysis'); legend('E-Plane','H-Plane'); grid on; axis([0 360 -60 0]); % Figure 2 figure(2) ht1=polar(x*pi/180,q1,'b-');

hold on; ht2=polar(x*pi/180,q2,'r--'); set([ht1 ht2],'linewidth',2); legend([ht1 ht2],{'E-plane','H-plane'}); title('Field patterns'); % Directivity Output directivity = 10*log10(DP) % Fresnel Subfunction function[y] = Fresnel(x); A(1) = 1.595769140; A(2) = -0.000001702; A(3) = -6.808508854; A(4) = -0.000576361; A(5) = 6.920691902; A(6) = -0.016898657; A(7) = -3.050485660; A(8) = -0.075752419; A(9) = 0.850663781; A(10) = -0.025639041; A(11) = -0.150230960; A(12) = 0.034404779; B(1) = -0.000000033; B(2) = 4.255387524; B(3) = -0.000092810; B(4) = -7.780020400; B(5) = -0.009520895; B(6) = 5.075161298; B(7) = -0.138341947; B(8) = -1.363729124; B(9) = -0.403349276; B(10) = 0.702222016; B(11) = -0.216195929; B(12) = 0.019547031; CC(1) = 0; CC(2) = -0.024933975; CC(3) = 0.000003936; CC(4) = 0.005770956; CC(5) = 0.000689892; CC(6) = -0.009497136; CC(7) = 0.011948809; CC(8) = -0.006748873; CC(9) = 0.000246420; CC(10) = 0.002102967; CC(11) = -0.001217930; CC(12) = 0.000233939; D(1) = 0.199471140; D(2) = 0.000000023; D(3) = -0.009351341; D(4) = 0.000023006; D(5) = 0.004851466; D(6) = 0.001903218; D(7) = -0.017122914; D(8) = 0.029064067; D(9) = -0.027928955; D(10) = 0.016497308; D(11) = -0.005598515; D(12) = 0.000838386; if(x==0) y=0; return

elseif(x<0) x=abs(x); x=(pi/2)*x^2; F=0; if(x<4) for(k=1:12) F=F+(A(k)+j*B(k))*(x/4)^(k-1); end y = F*sqrt(x/4)*exp(-j*x); y = -y; return else for(k=1:12) F=F+(CC(k)+j*D(k))*(4/x)^(k-1); end y = F*sqrt(4/x)*exp(-j*x)+(1-j)/2; y =-y; return end else x=(pi/2)*x^2; F=0; if(x<4) for(k=1:12) F=F+(A(k)+j*B(k))*(x/4)^(k-1); end y = F*sqrt(x/4)*exp(-j*x); return else for(k=1:12) F=F+(CC(k)+j*D(k))*(4/x)^(k-1); end y = F*sqrt(4/x)*exp(-j*x)+(1-j)/2; return end end

OUTPUT: E-Plane and H-Plane Horn Specifications

directivity = 18.8278 Horn Analysis 0 E-Plane H-Plane

Field Pattern (dB)

-10

-20

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-60

0

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150 200 Theta (degrees)

250

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Field patterns 90

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60 80

E-plane H-plane

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180

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