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Marina Lotti on 5 Mar 2021
Edited: David Goodmanson on 8 Mar 2021
Hello everyone,
I'm having some problems with a rotation of the antenna field. Here my antenna pattern now, after a decomposition of the theta and phi fields in x,y,z-ones:
and I'd like to rotate the main lobe along the x-axis. Do you have any idea to how I shoud do it? (without the phased array toolboox - so the rotpad function- because I do not have the toolboox).
I tried applying the matrix rotation on the 3(x,y,z)-components but it just gives me a kind of "change of name". Here the results:
But as you can see the main lobe is now in the z-component (right for my purpose) but not along the x-axis.
Thank you a lot in advance.
Bjorn Gustavsson on 8 Mar 2021
Marina, to me it sounds like you need to sketch this up from the beginning. Simply draw your two dipoles with their respective orientation and figure out what combinations of components you will detect. Further, I'd guess that you definitely dont need to "rotate the antenna-pattern", rather you need to get some combination of the H-field components - depending on your receiver orientation and position.

David Goodmanson on 8 Mar 2021
Edited: David Goodmanson on 8 Mar 2021
Hi Marina,
Since you are using surf, I am going to assume that you have three matrices x,y,z, each of size m x n, appropriate to feed into surf(x,y,z). Maybe this will help.
% simple example
thx = linspace(0,pi,40);
phix = linspace(0,2*pi,60);
[th phi] = meshgrid(thx,phix);
r = sin(th).*cos(th).*sin(phi);
x = r.*sin(th).*cos(phi);
y = r.*sin(th).*sin(phi);
z = r.*cos(th);
fig(1)
surf(x,y,z)
Rotate this through some arbitrary angles:
% rotate this through some arbitrary angles
xyz = [x(:) y(:) z(:)];
xyznew = xyz*Rxd(100)*Ryd(200)*Rzd(-300);
xnew = reshape(xyznew(:,1),size(x));
ynew = reshape(xyznew(:,2),size(x));
znew = reshape(xyznew(:,3),size(x));
surf(xnew,ynew,znew)
function M = Rxd(th)
% x rotation matrix
% angle is in DEGREES
% ccw rotation looking down at rotation axis up out of page
c = cosd(th);
s = sind(th);
M = [ 1 0 0;
0 c -s;
0 s c];
end
function M = Ryd(th)
% y rotation matrix
% angle is in DEGREES
% ccw rotation looking down at rotation axis up out of page
c = cosd(th);
s = sind(th);
M = [ c 0 s;
0 1 0;
-s 0 c];
end
function M = Rzd(th)
% z rotation matrix
% angle is in DEGREES
% ccw rotation looking down at rotation axis up out of page
c = cosd(th);
s = sind(th);
M = [ c -s 0;
s c 0;
0 0 1];
end