To find the open-circuit admittance parameter (Y21) of a two-port network, you'll need to follow these steps:
Set the output port (Port 2) to an open circuit: This means you disconnect any load or termination from Port 2, leaving it open.
Apply a test voltage at the input port (Port 1): To determine the open-circuit admittance, you'll need to apply a known voltage at Port 1. This voltage should be enough to create a measurable current through the open-circuited Port 2.
Measure the resulting current at Port 2: Use appropriate measurement tools, such as ammeters or current sensors, to measure the current flowing through the open-circuited Port 2.
Calculate the open-circuit admittance (Y21): Once you have the measured current (I) and the applied voltage (V) at Port 1, you can calculate the open-circuit admittance (Y21) using the following formula:
Y21 = I / V
Y21 is the open-circuit admittance from Port 1 to Port 2, given in units of Siemens (S) or mhos.
Remember that the open-circuit admittance parameter (Y21) represents the admittance between Port 1 and Port 2 of the two-port network when Port 2 is open-circuited. The open-circuit condition means that there is no load impedance connected to Port 2, allowing you to determine how the network responds when there is no external load connected.