Plotting Data in a 3D polar plot

I would like to plot the attached data (regarding antenna gain for different frequencies) as a 3D polar plot and I was hoping to find some function that takes theta, phi, and a radius as input (like the built in polarplot MATLAB function). I have looked Ken Garrad's and J De Freitas' 3D polar plotting functions but I don't know how to get my data formatted so that I can use their functions. I am relatively new to MATLAB so any help is much appreciated. I tried converting to Cartesian corrdinates and then plotting the data, but it does not display the data as clearly as I want.

[Anton Semechko]

"3D" polar plot is used for visualizing functions defined on a disk. The data you provided appears to be sampled on a spherical grid. How were you intending to visualize your data using 3D polar plot?

[Ben Bladow]

The goal would be to have the data be represented as a surface so that it is easier to read. (I have been struggling trying to use the meshgrid and surf fxns) The code below yields figures like the one attached.

for frequency = 1:201 % 201 total frequencies tested
  figure(frequency)  

    for theta = 1:19
       thetaDeg = (theta - 1) * 10;

       for phi = 1: 37
           phiDeg = (phi - 1) * 10;

           radius = dBLeft(phi, theta + (frequency-1) * 19);
           thetaRad = deg2rad(thetaDeg);
           phiRad = deg2rad(phiDeg);

           [X, Y, Z] = sph2cart(thetaRad, phiRad, radius);
           plot3(X,Y,Z, 'o', 'MarkerSize', 2);
           grid on
           hold on
       end
    end
    title(['Left Circular (dBi) for ', num2str(frequency + 819), ' MHz']);
    %Movie(frequency) = getframe;
    hold off
end

[Anton Semechko]

I just wanted to clarify a couple of things:

1) What do the entries in column A of the 'data.xls' file (ranging from 820 to 851) represent?

2) Does each block of data, corresponding to a specific entry in column A, represent samples acquired at the same radial distance, but different spatial directions?

[Ben Bladow]

1) Those are the different frequencies tested for gain, i.e. 820 MHz.

2) Same radial distance and same spatial directions (I believe... if I understand your question correctly).

[Anton Semechko]

Ok. So let's take the "data block" in 'data.xls' for 820 Hz, what are the Cartesian coordinates of the samples in cells C3 to C39? Please post the code used to obtain the answer on here.

Answer 1

[KSSV]

[num,txt,raw] = xlsread('data.xls') ;
th = num(1,3:end) ;
phi = num(3:39,3:end) ;

th = repmat(th,size(phi,1),1) ;

u = sin(th).*cos(phi) ;
v = sin(th).*sin(phi) ;

quiver(u,v)

https://in.mathworks.com/help/phased/ug/spherical-coordinates.html

[Ben Bladow]

Hey, thanks for the response. I tried out your code and I don't think a quiver graph helps make the data more visually readable. Of course it might just be because I don't know how to read one...