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Instead of reading where the plot intersects, read the numbers at the top
of the screen which is where your cursor is placed. You have: -0.774 dB loss at 54.6 + j 35.2 ohms equivalent of 64 ohms for the total impedance -0 440 dB loss at 80.7 + j 24.8 ohms equivalent of 84 ohms for the total impedance The total impedance is derived by calculating the SQRT of the SUM of the SQUARES. Note that using the reflection measurement option as illustrated in the first image, the total loss is 0.5 of the measured value as the RF must pass twice through the network. The ratios above don't change. So the loss at nominally 54 ohms real is 0.167 dB greater at 81 ohms real. Also note that due to the non 50-ohm or non 72-ohm Zo of the transmission line transformer (common mode choke), the Zo of the choke will transform either resistance to something else between 50 and 80-ohms. What you are using for your 50 and 72 ohm non-reactive loads for the load in your common mode choke - the disc in the first picture? How did you measure the impedance of our common mode choke? I usually take two measurements to determine this: 1) Measure the capacitance with the far end of the choke open terminated. This will give you the capacitance of the windings (pretty close). 2) Measure the inductance with the far end of the choke short terminated. this will give you the inductance of the windings (pretty close). Measure both of these using the Smith Chart and the cursor. Then calculate the characteristic impedance of the transmission line choke (common mode choke) using the following: Zo = SQRT [Measured Inductance in Henries / Measured Capacitance in Farads] NOTE: 1 ?H = 1E-6 H and 1 pF = 1E-12 F Dave - W?LEV both the On Sun, May 11, 2025 at 6:03?PM Team-SIM SIM-Mode via groups.io <sim31_team= [email protected]> wrote: Hi All-- *Dave - W?LEV* -- Dave - W?LEV |
