Difficulty getting power on an Airplane Radar project

Question

Tino Veitengruber 2022-7-29

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https://ww2.mathworks.cn/matlabcentral/answers/1770775-difficulty-getting-power-on-an-airplane-radar-project

回答： Sai Kiran 2022-10-19

I've got an issue with a matlab code I'm writing. I am attempting to plot the variable t, which is time, against the power variable. The issue is that matlab doesn't create an array for time that is matching the array for Gain. It seems to me that this is why the division for power isn't sucessful. Ive included the full code below in. I would appreciate any help that could be given!

clc; clear; close all;

N = 20; % Number of elements

M = 50; % IDK

Bd = pi/4; % Beta*distance between elements

phi = linspace(0,2*pi,300); % also dont exactly know

for i = 1:M

%% Power Pattern

alpha = 8*Bd*i/M; % Might have to change

psi = (Bd * cos(phi)) + (alpha);

F_array = (abs(sin(N*psi/2)./sin(psi/2))).^2; % Power radiation pattern

F_array_max = 400; % N^2

Pn = F_array / F_array_max; % Normalized power radiation pattern; max value 1

subplot(2,2,1)

polarplot(phi,Pn);

rlim([0 1])

%% Airplane Travel

t = 0:1:i; % makes t a function of time

z = (5000 - (t*(100))); % distance to airplane with time

theta = asin(500./z); % angle to airplane with time

subplot(2,2,2)

polarplot(theta,z);

%% Airplane Power Recieved

D = 1.64*( (cos(90*cos(psi))) / (((sin(psi))).^2));

Gain = (D * F_array).^2;

r = sqrt(250000 + z.^2);

Power = Gain / (r.^4);

subplot(2,2,3)

plot(t, Gain,'*')

pause(.5)

end;

Error using /
Matrix dimensions must agree.

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Tino Veitengruber 2022-7-31

Sure! I can try to elaborate a little more. Its an algorithem for determining the power pattern of a radar antenna in the first section. In the second second, the travel of the airplane itself is plotting using a polar plot. Lastly, the last part should calculate power recieved using the formula that the power = gain/r

r is a continually changing variable as the hypothenus from the antenna to a height at 500 meter. This radius is dependent on the changing angle. The plane is flying at 100m/s in the direction of the antenna. This leads to the adjacent side becoming z = 5000-100*t . Additionally, D is a gain constant for a half wave dipole antenna. This gain changes based on the angle to the aircraft as mentioned above. This gain constant is multiplied times the gain of the array which is F_array. I appreciate the help. I can also elaborate more if its still not clear.

Tino Veitengruber 2022-7-31