What's the physical significance of the complex field plots generated by EHfields and fieldsCustom?

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Chi Zhang
Chi Zhang on 28 Apr 2020
Edited: Chi Zhang on 28 Apr 2020
In the Antenna Toolbox, EHfields can generate complex fields of an antenna. EHfields and fieldsCustom can plot 3-by-p complex vectors.
From the complex fields at one moment, we can derive the field at any time. I made an animation of the transient H fields in a period, and found that there is no frame consistent with the plot generated by fieldsCustom.
load fielddata;
acf = 0.15;
f1 = fieldsCustom(acf*H,p);
f1.AutoScale = 'off';
ax1 = gca;
ax1.ZLim = [0 0.02];
hold on
Hmag = abs(acf*H); Hang = angle(H);
phi = pi/100:pi/100:2*pi;
% the curve traced by the end point of H field vector of point #61
ind = 61;
Hs = Hmag(:,ind).*cos(Hang(:,ind)+phi)+p(:,ind);
f2 = plot3(Hs(1,:),Hs(2,:),Hs(3,:),'k-');
% animation of transient H fields
f3 = quiver3(p(1,:),p(2,:),p(3,:),real(H(1,:)),real(H(2,:)),real(H(3,:)),...
'AutoScale','off');
hold off
for i = 1:length(phi)
Ht = Hmag.*cos(Hang+phi(i));
f3.UData = Ht(1,:);
f3.VData = Ht(2,:);
f3.WData = Ht(3,:);
pause(0.05)
end
As we know, amid three components of magnetic fields there may be phase shifts, thus the polariztion would be elliptical. A vector plotted by fieldsCustom does not locate in the plane where the curve traced by the end point of the corresponding transient vector is in.
What are the formulae of the plots generated by fieldsCustom? I made a comparison between the UData of fieldsCustom and abs of x componet of H field.
figure(2)
plot(1:121,f1.UData,'x',1:121,-Hmag(1,:),'o')
legend('fieldsCustom','minus abs')
The abs of U data of fieldsCustom equals the abs of x componet of H field, but the relation of signs between them is not clear, so as the V, W data. And I plot the abs of H field. It can be seen that, the corresponding two vectors may be the same, or in the opposite direction, or symmetric with a plane.
figure(3); hold on;
f31 = fieldsCustom(H,p);
f31.AutoScale = 'off';
quiver3(p(1,:),p(2,:),p(3,:),abs(H(1,:)),abs(H(2,:)),abs(H(3,:)),...
'AutoScale','off');
Now I'm confused about what is plotted by fieldsCustom or EHfields, and what is the physical significance of that visualization.

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