Inverse Synthetic Aperture Radar Imaging With MATLAB Algorithms. Caner Ozdemir

“Figure2 ‐ 15.m”

%-------------------------------------------------------- % This code can be used to generate Figure 2.15 %-------------------------------------------------------- clear close all c=.3; % speed of light [] f=2:.002:22; % choose frequency vector Ro=50; % choose range of target [m] k=2*pi*f/c; Es=1*exp(-1i*2*k*Ro); % collected SFCW electric field df=f(2)-f(1); % frequency resolution N=length(f); % total stepped frequency points dr=c/(2*N*df); % range resolution R=0:dr:dr*(length(f)-1); %set the range vector plot(R, 20*log10(abs(ifft(Es))),'k','LineWidth',2) grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\itrange, m'); ylabel('\itamplitude, dBsm'); axis([0 max(R) -90 0])

      Matlab code 2.4 Matlab file “Figure2 ‐ 16.m”

%--------------------------------------------------------- % This code can be used to generate Figure 2.16 %--------------------------------------------------------- clear close all t=0:0.01e-9:50e-9; % choose time vector N=length(t); pulse(201:300)=ones(1,100); % form rectangular pulse pulse(N)=0; % Frequency domain equivalent dt=t(2)-t(1); % time resolution df=1/(N*dt); % frequency resolution f=0:df:df*(N-1); % set frequency vector pulseF=fft(pulse)/N; % frequency domain signal %---Figure 2.16(a)------------------------------------------ plot(t(1:501)*1e9,pulse(1:501),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\ittime, ns'); ylabel('\itamplitude, V'); axis([0 5 0 1.1]); %---Figure 2.16(b)------------------------------------------ figure plot(f(1:750)/1e9,20*log10(abs(pulseF (1:750))),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); axis([0 f(750)/1e9 -85 -20]); xlabel('\itfrequency, GHz'); ylabel('\itamplitude, dB');

      Matlab code 2.5 Matlab file “Figure2 ‐ 17.m”

%--------------------------------------------------------- % This code can be used to generate Figure 2.17 %--------------------------------------------------------- clear close all t=-25e-9:0.01e-9:25e-9; % choose time vector N=length(t); sine(2451:2551)=-sin(2*pi*1e9*(t(2451:2551))); % form sine pulse sine(N)=0; % Frequency domain equivalent dt=t(2)-t(1); % time resolution df=1/(N*dt); % frequency resolution f=0:df:df*(N-1); % set frequency vector sineF=fft(sine)/N; % frequency domain signal %---Figure 2.17(a)------------------------------------------------ plot(t(2251:2751)*1e9,sine (2251:2751),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\ittime, ns'); ylabel('\itamplitude, V'); axis([-2.5 2.5 -1.1 1.1]); %---Figure 2.17(b)------------------------------------------------ figure plot(f(1:750)/1e9,20*log10(abs(sineF (1:750))),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); axis([0 f(750)/1e9 -85 -20]); xlabel('\itfrequency, GHz'); ylabel('\itamplitude, dB');

      Matlab code 2.6 Matlab file “Figure2 ‐ 18.m”

%--------------------------------------------------------- % This code can be used to generate Figure 2.18 %--------------------------------------------------------- clear close all sigma=1e-10; % set sigma t=-25e-9:0.01e-9:25e-9; % choose time vector N=length(t); mex(2451:2551)=1/sqrt(2*pi)/sigma^3*(1-t(2451:2551). ^2/sigma^2)... .*(exp(-t(2451:2551).^2/2/sigma^2)); % form wavelet mex=mex/max(mex);mex(N)=0; % Frequency domain equivalent dt=t(2)-t(1); % time resolution df=1/(N*dt); % frequency resolution f=0:df:df*(N-1); % set frequency vector mexF=fft(mex)/N; % frequency domain signal %---Figure 2.18(a)------------------------------------------------ plot(t(2251:2751)*1e9,mex(2251:2751),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\ittime, ns'); ylabel('\itamplitude, V'); axis([-2.5 2.5 -.5 1.1]); %---Figure 2.18(a)------------------------------------------------ figure plot(f(1:750)/1e9,20*log10(abs(mexF (1:750))),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); axis([0 f(750)/1e9 -180 -40]); xlabel('\itfrequency, GHz'); ylabel('\itfAmplitude, dB');

      Box Matlab code 2.7 Matlab file “Figure2 ‐ 19and20.m”

%--------------------------------------------------------- % This code can be used to generate Figure and Figure 2.19 %--------------------------------------------------------- clear close all fo=1e6; % choose base frequency t=0:1e-9:4e-6; tt=0:1e-9:17e-6; % choose time vector k=1.0e12; % choose chirp rate sinep=sin(2*pi*fo*t);sinep(12001:16001)=sinep; % form CW pulse sinep(17001)=0; m=sin(2*pi*(fo+k*t/2).*t); % form LFM pulse m(12001:16001)=m; m(17001)=0; %---Figure 2.19(a)------------------------------------------ plot(tt*1e6,sinep,'k','LineWidth',2); set(gca,'FontName', 'Arial', 'FontSize',14,'FontWeight','Bold'); xlabel('Time [\mus]'); ylabel('Amplitude [V]'); axis([0 17 -1.1 1.1]) %---Figure 2.19(b)------------------------------------------ plot(tt*1e6,m,'k','LineWidth',2); set(gca,'FontName', 'Arial', 'FontSize',14,'FontWeight','Bold'); xlabel('Time [\mus]'); ylabel('Amplitude [V]'); axis([0 17 -1.1 1.1]) % Frequency domain equivalent df=1/170e-6; % frequency resolution f=0:df:df*170000; % set frequency vector sinep=sin(2*pi*fo*t);sinep(170001)=0; m=sin(2*pi*(fo+k*t/2).*t); m(170001)=0; fsinep=fft(sinep)/length(t); % spectrum of CW pulse fm=fft(m)/length(t);% spectrum of LFM pulse %---Figure 2.20(a)------------------------------------------------ plot(f(1:2000)/1e6,20*log10(abs(fsinep(1:2000))),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\itfrequency, MHz'); ylabel('\itAmplitude, dB'); % text(8,-10,'Single tone pulse') axis([0 12 -40 -5]) %---Figure 2.20(b)------------------------------------------------ figure plot(f(1:2000)/1e6,20*log10(abs(fm (1:2000))),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\itfrequency, MHz'); ylabel('\itamplitude, dB'); % text(8,-10,'Chirp pulse') axis([0 12 -40 -5])

References

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      2 Balanis, C.A. (1989). Advanced Engineering Electromagnetics. New York: Wiley.

      3 Bhalla, R. and Ling, H. (1993). ISAR image formation using bistatic data computed from the shooting and bouncing ray technique. Journal of Electromagnetic Waves and Applications 7 (9): 1271–1287.

      4  Bhalla, R. and Ling, H. (1995). A fast algorithm for signature prediction and image formation using the shooting and bouncing ray technique. IEEE Transactions on Antennas and Propagation 43 (7): 727–731.

      5 Brummund, U. and Mesnier, B. (1999). A comparative study of planar Mie and Rayleigh scattering for supersonic flowfield diagnostics. 18th International Congress Instrumentation in Aerospace Simulation Facilities (ICIASF 99), Toulouse, France, IEEE Record (Cat. No.99CH37025), 42/1‐4210.

      6 Chu, T.H., Lin, D.B., and Kiang, Y.W. (1991). Microwave diversity imaging of perfectly conducting objects in the near field region. IEEE Transactions on Microwave Theory and Techniques 39: 480–487.

      7 Crispin, J.W. and Siegel, K.M. (1970). Methods for Radar Cross‐Section Analysis. New York: Academic.

      8 Ekelman, E. and Thiele,