How to draw the log polar diagram and linear cartesian diagram of this code?

Here is the code. It is currently a linear polar diagram. How to draw a log polar diagram (dB=20loglinear) and a linear cartesian diagram about this ?

clear all;

% element numbers

N = 8;

% element spacing

wl = 1;

k = 2.*pi./wl;

d = wl./2;

% theta zero direction

% 90 degree for braodside, 0 degree for endfire.

%theta_zero = 90;

An = 1;

j = sqrt(-1);

AF = zeros(1,180);

for theta=1:180

% change degree to radian

deg2rad(theta) = (theta*pi)/180;

%array factor calculation

for n=1:N

AF(theta) = AF(theta) + exp((-1j).*k.*(n-1).*d.*sin (deg2rad(theta))) ;

end

AF(theta) = abs(AF(theta));

end

[Athrey Ranjith Krishnanunni]

>>It is currently a linear polar diagram.

There aren't any plotting functions in the code that you have posted, so what do you mean?

Also, use the code view (or Alt + Enter) to properly format your code

like this

so that it's easier to read and understand.

[ZIYI WENG]

Sorry I missed the final step

% plot the array factor

polar(deg2rad,AF);

clear all;
% element numbers
N = 8;

% element spacing
wl = 1;
k = 2.*pi./wl;
d = wl./2;

% theta zero direction
% 90 degree for braodside, 0 degree for endfire.
%theta_zero = 90;

An = 1;
j = sqrt(-1);
AF = zeros(1,180);

for theta=1:180
    
    % change degree to radian
    deg2rad(theta) = (theta*pi)/180;
    
    %array factor calculation
    for n=1:N
        AF(theta) = AF(theta) + exp((-1j).*k.*(n-1).*d.*sin (deg2rad(theta))) ;
    end
    AF(theta) = abs(AF(theta));
    
end

% plot the array factor
polar(deg2rad,AF);

[Athrey Ranjith Krishnanunni]

Doesn't

polar(deg2rad,20*log10(AF))

work for the log-polar plot?

And by cartesian, do you mean something other than

plot(deg2rad,AF)

?

By the way, avoid defining variables to have the same name as default MATLAB functions, e.g. deg2rad, and also you don't need to write

j = sqrt(-1);

especially considering that you're later using 1j anyway.

[ZIYI WENG]

Thanks!

What I meant for linea cartesian plot is that I want the x-axis shows as angle but not radians. However, this programme seems not working when I use angle instead radian.

[Alan Stevens]

"What I meant for linea cartesian plot is that I want the x-axis shows as angle but not radians. However, this programme seems not working when I use angle instead radian."

Try

plot(rad2deg(theta),AF)

[Athrey Ranjith Krishnanunni]

@ZIYI WENG that's an easy problem to fix, but since the variable names in your codes are... not the best, the solution will be horrendous. I've attempted to change that by using angle_rad instead of deg2rad:

for theta=1:180
    
    % change degree to radian
    angle_rad(theta) = (theta*pi)/180;
    
    %array factor calculation
    for n=1:N
        AF(theta) = AF(theta) + exp((-1j).*k.*(n-1).*d.*sin (angle_rad(theta))) ;
    end
    AF(theta) = abs(AF(theta));
    
end

polar(angle_rad,AF) % linear polar plot
polar(angle_rad,20*log10(AF)) % "log-polar" plot
plot(rad2deg(angle_rad),AF) % linear cartesian plot, with x-axis in degrees

@Alan Stevens's answer works if you write

plot(rad2deg(deg2rad),AF)

instead, which is a nightmare for anyone reading your code.

[Alan Stevens]

"plot(rad2deg(deg2rad),AF)

which is a nightmare for anyone reading your code."

I agree!! I wrote that after I had gone through the original program and used theta in radians from the start!

[ZIYI WENG]

Thanks a lot!