To find the short-circuit admittance parameter (Y12) of a two-port network, you typically follow these steps:
Understand the Two-Port Network:
A two-port network consists of two input terminals (port 1) and two output terminals (port 2). The short-circuit admittance parameter, Y12, represents the admittance between port 1 and port 2 when port 2 is short-circuited.
Apply Short Circuit at Port 2:
To find Y12, you need to short-circuit port 2. This means you connect the two terminals of port 2 together with a wire (a short circuit).
Disconnect All Independent Sources:
If the network contains independent sources (voltage or current sources), you need to temporarily disconnect them. This is because you are looking for the short-circuit response, and the presence of independent sources would affect the results.
Measure Current at Port 1:
With port 2 short-circuited and independent sources disconnected, you measure the current flowing into or out of port 1 (I1). Depending on your convention, the current direction may be considered positive if it flows into port 1 or negative if it flows out.
Measure Voltage at Port 1:
Next, measure the voltage at port 1 (V1). Again, depending on the convention, the voltage may be considered positive if it is higher at terminal 1 relative to terminal 2 or negative if it is lower at terminal 1 compared to terminal 2.
Calculate the Short-Circuit Admittance (Y12):
Finally, the short-circuit admittance parameter (Y12) can be calculated using the following formula:
Y12 = I1 / V1
where I1 is the measured current at port 1, and V1 is the measured voltage at port 1.
It's worth noting that the short-circuit admittance parameter Y12 is just one of the four commonly used parameters to describe a two-port network. The others are:
Y11: Admittance between port 1 and port 1 with port 2 open-circuited.
Y21: Admittance between port 2 and port 1 with port 2 open-circuited.
Y22: Admittance between port 2 and port 2 with port 1 open-circuited.
Remember that the conventions for the positive directions of current and voltage may vary depending on the specific context or notation used. Always check the documentation or context to ensure you use the correct conventions for your calculations.