MATLAB: How does Antenna Toolbox sparameters treat load impedance

Antenna Toolboxworkspace

I've created and installedAntenna object with two monopole antennas as elements, each with a load impedance. When I calculate the S-parameters, S_22 behaves as expected, but S_11 seems unchanged regardless of what I set the load impedance to. Interestingly, if I change the reference impedance in the sparameter function, then both S_11 and S_22 change. What happening under the hood of the Antenna Toolbox that's causing this? Here's a snipet of my code:
freq = 150e6;
ant1 = design(monopole,freq);
ant1.Height = 0.3556;
ant1.Load = lumpedElement('Impedance',400+50i);
ant2 = design(monopole,freq);
ant2.Height = 0.3556;
ant2.Load = lumpedElement('Impedance',30-13i);
ant = installedAntenna;
ant.ElementPosition = [-0.5, -0.5, 0.1; 0.5, 0.5, 0.1];
ant.Element = {ant1, ant2};
S = sparameters(ant, linspace(100e6, 400e6, 100));
%S = sparameters(ant, linspace(100e6, 400e6, 100),100); Uncomment this and comment the line above to use 100ohm ref impedance
tiledlayout(2,2)
nexttile
rfplot(S,1,1)
nexttile
rfplot(S,1,2)
nexttile
rfplot(S,2,1);
nexttile
rfplot(S,2,2);

Best Answer

I have heard that this issue is known and will be fixed in future releases.
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