reflection coefficient are both below -10dB at 1GHz and the overall |s12| of the circuit is negligible.
{| border="0"<table>|-<tr>| valign="bottom"|<td>[[File:RF115.png|thumb|900px|left750px|The graph of magnitude of s11, s21, s12 and s22 parameters of the BJT amplifier circuit.]]|-</td>|}</tr></table>
[[File:RF135.png|thumb|450px|The RF BJT Amplifier with S-parameter RF BJT model for AC network analysis.]]
Keep in mind that the results you obtained so far included the source and load resistors. They represent the S-[[parameters]] of your overall network. For the purpose of our analysis and comparison with the results of the next part, it is instructive to remove the source and load resistors and run a Network Analysis Test of the true amplifier circuit independent of the source and load. The opposite figure shows this circuit with the source and load sections removed. Run an AC Network Analysis Test of this modified circuit with the exactly the same settings as in the previous case. The results are shown in the figure below. Note how the value of |s21| at 1GHz has jumped to 15.385dB this time around, while the total input and output reflection coefficients are still both below -10dB. This validates your design strategy based on the unilateral assumption. You will see in the next section that the computed values of |s21| (insertion loss or gain) is very close to the computed value of the power gain from the source to the load.
{| border="0"<table>|-<tr>| valign="bottom"|<td>[[File:RF134.png|thumb|900px|left750px|The graph of magnitude of s11, s21, s12 and s22 parameters of the BJT amplifier circuit without the source and load sections.]]|-</td>|}</tr></table>
[[File:RF133.png|thumb|640px|The RF BJT Amplifier with S-parameter RF BJT model for AC frequency sweep test including source and load ammeters.]]
== Running an AC Frequency Sweep Test of the BJT Amplifier ==
<table>
<tr>
<td>
[[File:RF133.png|thumb|640px|The RF BJT Amplifier with S-parameter RF BJT model for AC frequency sweep test including source and load ammeters.]]
</td>
</tr>
</table>
In the last part of this tutorial lesson, you will run an AC Sweep Test of your BJT amplifier circuit to examine the input and output voltages and find the voltage gain and power gain of your amplifier. To measure the power gain, we define input and output powers as the source and load powers: