Figure 16. Clutter Eigenspectra with Misalignment for Different Backlobe Levels.

Contents

Coded by Ilias Konsoulas, 16 Sept. 2018.
Code provided for educational purposes only. All rights reserved.
clc; clear; close all;

Radar System Operational Parameters

radar_oper_params;

Platform Parameters

beta = 1;                       % beta parameter.
phia = 10;                      % misalignment angle in degrees.
be = [-20 -30 -40 -50 -60 -70]; % Various backlobe power levels.

Thermal Noise Power Computations

thermal_noise_power;

Clutter Patch RCS Computation.

clutter_patch_rcs;

colors = [0 0 1; 0 1 0; 1 0 0 ; 1 1 0; 0 1 1; 1 0 1;];

Calculate the Array Factor (AF) (Voltage)

Nc = 360;
phi = -180:179;        % Azimuth angle in degrees:
Lphi = length(phi);
Gt = 22;               % Array Transmit Gain in dB
Gr = 10;               % Column Receive Gain in dB
Gel = 4;               % Element Gain in dB

f = zeros(1,Lphi);
AF = zeros(1,Lphi);

steering_angle = 0; % Angle of beam steering in degrees.
for k=1:Lphi
    AF(k) = sum(exp(-1i*2*pi/lambda*d*(0:N-1)*(sin(phi(k)*pi/180) - sin(steering_angle*pi/180))));
end

Calculate the Full Array Transmit Power Gain

Gtgain = 10^(Gt/10)*abs(AF).^2;

Calculate and Plot the Clutter Eigenspectrum for Different Backlobe Levels

figure('NumberTitle', 'off','Name', ...
       'Figure 16. Clutter Eigenspectra with Misalignment for Different Backlobe Levels', 'Position',[1 1 750 600]);

for i1=1:length(be)

    % Calculate the Voltage Element Pattern:
    for i =1:Lphi
        if abs(phi(i))<=90
            f(i) = cos(phi(i)*pi/180);
        else
            f(i) = 10^(be(i1)/10/2)*cos(phi(i)*pi/180);
        end
    end

    gel = abs(f).^2;  % Element Power Gain

    % Calculate the Full Array Transmit Power Gain.
    Gtgain = 10^(Gt/10)*(abs(AF).^2).*gel;

    % Calculate the Element Receive Power Gain:
    grgain = 10^(Gel/10)*gel;

    % Total Column Reception Gain:
    Grec = 10^(Gr/10)*grgain;

    ksi = Pt*Gtgain.*Grec*lambda^2*sigma/((4*pi)^3*Pn*10^(Ls/10)*Rcik^4);   % Eq. (58)

    Rc = clutt_cov2(ksi,beta,phia);

    plot(10*log10(abs(eig(Rc))),'--s','LineWidth',1,'Color', colors(i1,:), ...
         'MarkerEdgeColor','k','MarkerFaceColor',colors(i1,:), 'MarkerSize',5);
    hold on;
end

ylim([-80 80]); xlim([0 100]);
grid on;
legend('b_e = -20 dB', 'b_e = -30 dB', 'b_e = -40 dB', 'b_e = -50 dB', 'b_e = -60 dB', 'b_e = -70 dB');
ylabel('Relative Power (dB)'); xlabel('Eigenvalue Number');
title('Misalignment Angle: \phi_a = 10\circ');