Ratios   

The Ratios submenu selects and defines ratios of wave quantities.

Ratios

• b2/a1 Src Port 1, b1/a1 Src Port 1, b2/b1 Src Port 1, and b1/b2 Scr Port 1 select predefined ratios of the standard 2-port wave quantities a1, a2, b1, and b2, to be measured in forward direction with port 1 providing the stimulus signal.

• More Ratios opens a dialog to define and select arbitrary ratios of wave quantities for different detectors and source ports or more than 2 ports. .

In contrast to S-parameters, ratios are not system error corrected. A power calibration can be applied to ratios; see Data Flow.

b2/a1 Src Port 1, b1/a1 Src Port 1, b2/b1 Src Port 1, b1/b2 Src Port 1

Select predefined complex ratios of the standard 2-port wave quantities a1, a2, b1, and b2:

The predefined wave quantities are all obtained with the same test set configuration, port 1 providing the stimulus signal (source port 1, forward measurement if the stimulus signal is fed to the input of the DUT).

• b2/a1 Src Port 1 is the ratio of the wave quantities b2 and a1 and corresponds to the S-parameter S21 (forward transmission coefficient).

• b1/a1 Src Port 1 is the ratio of the wave quantities b1 and a1, measured at PORT 1, and corresponds to the S-parameter S11 (input reflection coefficient).

• b2/b1 Src Port 1 is the ratio of the transmitted to the reflected wave quantities in a forward measurement.

• b1/b2 Src Port 1 is the inverse of b2/a1 Src Port 1.

The analyzer can also measure arbitrary ratios for other source ports; see More Ratios.

More Ratios

Opens a dialog to select arbitrary ratios of wave quantities, e.g. for different detectors and source ports or more than 2 ports. .

The notation for ratios and the functionality of the More Ratios dialog is analogous to the definition of S-parameters.

• Numerator selects the type (left pull-down list) and the port number assignment (right pull-down list) of the wave that forms the numerator of the ratio. The input (stimulus) or output (response) port number is selected in the right pull-down list. The range of output and input port numbers depends on the analyzer model.

• Denominator selects the type (left pull-down list) and the port number assignment (right pull-down list) of the wave that forms the denominator of the ratio. The same waves as for the Numerator are available.

• Ratio indicates the selected ratio.

• Source Port contains all analyzer ports or external generators which can be used as a source for the stimulus signal. The list contains all analyzer ports Port 1 to Port n. Generators (Gen 1, Gen 2, ...) must be configured explicitly in the System Configuration – External Generators dialog before they appear in the list.  

• Detector selects the algorithm that is used to calculate the displayed trace from the individual measurement points. In the Max. and RMS detector modes, it is possible to define the detector observation time (Meas. Time) for a single measurement point.

External generators

Detector

Selects the algorithm that is used to calculate the displayed measurement points from the raw data. The Detector can be selected in the More Ratios and More Wave Quantities dialogs.

The following detectors are available:

• Normal selects the default detector mode where each measurement point is displayed without modification as soon as it is recognized to be valid. The analyzer then proceeds to the next sweep point. Normal detector mode ensures that the measurement is performed at maximum speed and that a meaningful complex result is obtained.  

• Peak collects all valid results at each sweep point during the Meas. Time set in the More Ratios or More Wave Quantities dialog and selects the result with the maximum magnitude (maximum power) as the measurement point. The imaginary part of the measurement point is set to zero.

• RMS collects all valid results at each sweep point during the Meas. Time set in the More Ratios or More Wave Quantities dialog and calculates the root mean square (RMS) of the of these results. This yields the real part of the measurement point. Averaging the phase does not make sense so the imaginary part of the measurement point is set to zero.  

The detector settings have an influence on the displayed trace. They do not affect the number of measurement points in a sweep (or in a subset of the sweep range) but may increase the sweep time In the Peak and RMS detector settings, the sweep time can not be smaller than the detector observation time (Meas. Time) set in the More Ratios or More Wave Quantities dialogs. The sweep time can be larger if additional delays are taken into account. Changing the Meas. Time affects the sweep time. On the other hand, increasing the Sweep Time in the Channel – Sweep menu leaves the Meas. Time unchanged.

Combining different detectors