MATLAB Examples

# Figure 6. The β=1 Clutter Ridge.

## Contents

clc; clear; close all; 

fo = 450e6; % Operating Frequency in Hz Pt = 200e3; % Peak Transmit Power 200 kW Gt = 22; % Transmit Gain in dB Gr = 10; % Column Receive Gain in dB B = 4e6; % Receiver Instantaneous Bandwidth in Hz Ls = 4; % System Losses in dB fr = 300; % PRF in Hz Tr = 1/fr; % PRI in sec. % M = 18; % Number of Pulses per CPI: Tp = 200e-6; % Pulse Width in sec. N = 18; % Number of Array Antenna Elements Gel = 4; % Element Gain in dB be = -30; % Element Backlobe Level in db Nc = 361; % Number of clutter patches uniformly distributed in azimuth. c = 299792458; % Speed of Light in m/sec. lambda = c/fo; % Operating wavelength in meters. d = lambda/2; % Interelement Spacing. % Azimuth angle in degrees: phi = -180:.5:180; Lphi = length(phi); 

## Platform Parameters:

va = 50; % Platform velocity in m/sec. ha = 9e3; % Platform altitude in meters. Rc = 13e4; % (clutter) range of interest in meters. psi = asin(ha/Rc); % Grazing angle at the clutter patch in rad (flat earth model). theta = psi; % Depression angle to ik-th clutter patch (flat earth model). 

## Spatial Frequency of ik-th Clutter Patch:

fsp = d/lambda*cos(theta)*sin(phi*pi/180); % Eq. (54) % Doppler Frequency of ik-th Clutter Patch: fd = 2*va/lambda*cos(theta)*sin(phi*pi/180); % Eq. (69) % Normalized Doppler Frequency: omegac = 2*va*Tr/d*fsp; % Eq. (70) beta = 2*va*Tr/d; % Eq. (71) 

## Plot Doppler Frequency vs Azimuth and Normalized Doppler Frequency vs Spatial Frequency.

figure('NumberTitle', 'off','Name',... ['Figure 6. The β =1 clutter ridge for Side Looking Airborne Radar (SLAR). The PRF is ', ... num2str(fr),' Hz.'],'Position', [50 50 900 400] ); subplot(1,2,1); plot(sin(phi*pi/180),fd,'.'); grid on; ylabel('Doppler Frequency f_c(\theta_c,\phi_c) (Hz)'); xlabel('sin(\phi_c)'); subplot(1,2,2); plot(fsp,omegac,'.'); grid on; ylabel('Normalized Doppler Frequency \omega_c'); xlabel('Spatial Frequency \vartheta_c');