#### Admittance

The Admittance submenu contains the functions to convert reflection S-parameters into matched-circuit admittances.

Matched-circuit admittances and short-circuit Y-parameters

The analyzer provides two different types of admittance parameters that are essentially based on different n-port circuit models:

- The matched-circuit admittances describe the admittances of a DUT that is terminated at its outputs with the reference impedance Z0.

- The short-circuit Y-parameters describe the admittances of a DUT with output ports terminated in a short circuit (V = 0). Short-circuit Y-parameters can be selected in the More Y-Parameters dialog.

Mixed mode measurements are available for both types of admittance parameters.

- Y <– S11, Y <– S12, Y <– S21, Y <– S22
  select the forward or reverse matched-circuit admittances of a 2-port DUT.

- More Admittances
  ... opens a dialog to define and select short-circuit admittances for more ports or mixed mode measurements.

##### Y <– S11, Y <– S12, Y <– S21, Y <– S22

Select the 2-port converted matched-circuit admittance parameters. The parameters describe the admittances of a 2-port DUT, obtained in forward and reverse transmission and reflection measurements:

- Y11 is the input admittance of a 2-port DUT that is terminated at its output with the reference impedance Z0 (matched -circuit admittance measured in a forward reflection measurement).

- Y22 is the output admittance of a 2-port DUT that is terminated at its input with the reference impedance Z0 (matched -circuit admittance measured in a reverse reflection measurement).

- Y12 and Y21 denote the forward and reverse transfer admittances, respectively.

The analyzer can also provide matched-circuit admittances for more drive ports or balanced port configurations; see More Admittances
.

Relation with S-parameters

Use the More Y-Parameters
dialog to measure short-circuit Y-parameters including the transfer parameters. Use the Inverted Smith chart
to obtain an alternative, graphical representation of the converted admittances in a reflection measurement.

Remote control: | CALCulate<Ch>:PARameter:MEASure "<Trace_Name>", "Y-S11" | "Y-S12" | "Y-S21" | "Y-S22" [SENSe<Chn>:]FUNCtion[:ON] "...:POWer:Y<11 | 12 | 21 | 22>" Create new trace and select name and measurement parameter: CALCulate<Ch>:PARameter:SDEFine "<Trace_Name>", "Y-S11" | "Y-S12" | "Y-S21" | "Y-S22"

##### More Admittances

Opens a dialog to select converted, matched-circuit admittances for more ports or balanced port measurements.

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

- Y<— selects the type (left pull-down list) and the port number assignment (right pull-down list) of the admittance parameter. Mixed mode parameters are only available if a balanced port configuration is active. They are expressed as Y<mout><min>, where <mout> and <min> denote the output and input port modes. The port numbers are assigned in the order Y<out>< in>, where <out> and <in> denote the output (response) and input (stimulus) port numbers of the DUT.

- Balanced and Measured Ports
  opens the dialog of the same name to define the properties of the test ports. Single-ended (unbalanced) admittance parameters are assigned to the physical test ports of the analyzer. Balanced admittance parameters are assigned to logical test ports. Selecting a balanced port configuration with logical test ports means that the unbalance-balance conversion
  is switched on and that the analyzer provides mixed mode parameters
  .

- The graphics above the Balanced and Measured Ports button illustrates the current port configuration.

The port configuration is valid for all traces in the channel

The settings made in the Balanced and Measured Ports dialog are channel settings and therefore apply to all traces assigned to the channel (Balanced and Measured Ports is also accessible through Channel –Mode–Port Config...). Within a channel the analyzer measures either single-ended or mixed mode parameters. If a balanced test port configuration is selected the single-ended parameters assigned to the channel are converted into mixed mode parameters.

Single-ended and mixed mode parameters

The relation between the generalized (multiport and mixed mode) admittance parameters and the S-parameters is analogous to the 2-port case and follows from the relations for impedance parameters
.

Remote control: | CALCulate<Ch>:PARameter:MEASure "<Trace_Name>", "Y-S11" | "Y-S12" ... Create new trace and select name and measurement parameter: CALCulate<Ch>:PARameter:SDEFine "<Trace_Name>", "Y-S11" | "Y-S22" | ...