E.3 Mismatch uncertainty of the RF relay

37.5443GPPConformance testingRelease 16TSUniversal Terrestrial Radio Access (UTRA) and Evolved UTRA (E-UTRA)User Equipment (UE) Over The Air (OTA) performance

If the same receiver chain configuration (including the measurement receiver; the probe antenna and other elements) is used in both stages, the uncertainty is considered systematic and constant  0.00dB value.

If it is not the case, this uncertainty contribution has to be taken into account and determined by the following method.

The following figure describes the RF Relay with its ‘S’ parameters and the complex reflection coefficient of the inputs and output:

Figure E.3-1: Mismatch uncertainty of the RF relay

The RF relay is used to switchover the cross and direct polarization signals from the probe antenna. To determine RF Relay mismatch uncertainty contributions, reflection coefficients for each port and the cross talk attenuation have to be known.

The total combined mismatch uncertainty is composed of two parts:

1) The mismatch uncertainty contributions when the RF Relay switches on the direct polarization signal

2) The mismatch uncertainty contributions when the RF Relay switches on the cross polarization signal

Each part is composed of two types of uncertainties introduced in the previous paragraph: the mismatch through the connector between two elements and the mismatch due to the interaction between several elements.

E.3.1 First part: RF Relay switched on the co-polarized signal

E.3.1.1 The mismatch through the connector between two elements

Between the Input1 and the port1:

U_mismatch1(dB) =

Between the port3 and the Output:

U_mismatch2(dB) =

Between the Input2 and the port2:

The RF Relay switchovers on the direct polarization signal. As a result, there is no mismatch uncertainty contribution.

E.3.1.2 Mismatch due to the interaction between two elements or more

Between the Input1 and the Output:

U_interaction1(dB) =

Between the Input1 and the Input2:

U_interaction2(dB) =

The RF Relay switchovers on the cross polarization signal. As a result; this uncertainty contribution is usually disregarded because of the high crosstalk attenuation which is characterized by and ‘S’ parameters. If the crosstalk attenuation is low, this uncertainty contribution has to be considered.

Between the Input2 and the Output:

U_interaction3(dB) =

The RF Relay switchovers on the cross polarization signal. As a result; this uncertainty contribution is usually disregarded because of the high cross-talk attenuation, which is characterized by and ‘S’ parameters. If the crosstalk attenuation is low, this uncertainty contribution has to be considered.

E.3.2 Second part: RF relay switched on the cross-polarized signal

E.3.2.1 The mismatch through the connector between two elements

Between the Input1 and the port1:

The RF Relay switchovers on the direct polarization signal. As a result, there is no mismatch uncertainty contribution.

Between the port3 and the Output:

U_mismatch3(dB) =

Between the Input2 and the port2:

U_mismatch4(dB) =

E.3.2.2 Mismatch due to the interaction between two elements or more

Between the Input1 and the Output:

U_interaction4(dB) =

The RF Relay switchovers on the cross polarization signal. As a result; this uncertainty contribution is usually disregarded because of the high crosstalk attenuation which is characterized by and ‘S’ parameters. If the crosstalk attenuation is low, this uncertainty contribution has to be considered.

Between the Input1 and the Input2:

U_interaction5(dB) =

The RF Relay switchovers on the cross polarization signal. As a result; this uncertainty contribution is usually disregarded because of the high crosstalk attenuation which is characterized by and ‘S’ parameters. If the crosstalk attenuation is low, this uncertainty contribution has to be considered.

Between the Input2 and the Output:

U_interaction6(dB) =

E.3.3 Total combined mismatch uncertainty

Each non-zero mismatch uncertainty contribution from both parts (RF Relay switched on the cross and direct polarization signal) are combined by the root-sum-squares (RSS) method to derive the total combined mismatch uncertainty.

The total combined mismatch uncertainty is equal to:

If a RF Relay is used to drive the cross and direct polarization signals from the dual-polarized antenna, this total combined mismatch uncertainty has to be added with all the uncertainty measurement contributions for the total combined measurement uncertainty.