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In first set of measurements we want to show how the signal strength changes for different slant angle (Tx-Rx orientation). On the left side, we can see 4 different figures which represent signal strength in each of the links of 2x2 MIMO system. Three different antenna configurations are considered: Cpol-Cpol, Xpol-Xpol, and Xpol-Cpol. Cpol-Xpol is not considered, because it is essentially the same as Xpol-Cpol. Let's take a look at top left figure. In there Cpol-Cpol an Xpol-Xpol have similar behavior with peaks 0 and 180 degrees (max) and 90 degrees (min). Xpol-Cpol has opposite pattern because in it two antennas are perpendicular for slant 0. For bottom right figure patterns for all three configuration match, because another element of Xpol is copolarized with both elements of Cpol. Top right and bottom left figures can be explain using same principle. Next, let's take a look at the right figure, which shows aggregated power, which is sum of squared magnitudes of all four links. Here, we can observe interesting result. For Xpol-Xpol and Xpol-Cpol antenna configurations overall magnitude is independent of slant angle, while strong variations are persistend for Cpol-Cpol configuration. |
IEEE/ICACT20210112 Slide.08
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