ECE 6180 Midterm I (Transmission Lines)

Name _____________________________

You may use your portfolio and calculator. No textbooks.

1. (33 points) Double Stub matching networks

Design a double stub matching network to connect a load that is 75 + j 50 ohms to a 50 ohm line. Use 100-ohm short-circuited stubs. There is no distance between the load and first stub. The length of 50-ohm line between the stubs is 0.04 wavelengths. Sketch your final design, labeling all lengths.

2. (33 points) L matching

1. Design an L-matching network to connect a load that is 75 ohms to a 50 ohm line. Use a high-pass design.
2. For a frequency of 1 GHz, specify the C and L values.
3. The circuit shown below was designed to match a load of 25 ohms to the generator. Specify C and L components for proper matching when the load is 25 – j 10 ohms. If you cannot absorb the load, describe in detail how to redo the problem using resonance (you do not need to do the actual calculations, but do specify each step).

3. (33 points) S/Z/Y Parameters

a. Sketch the RLGC circuit for a transmission line.

b. Find the Z-matrix using voltage and/or current dividers. You can leave your answers in terms of impedance equations (something like Z1 || Z2 is acceptable)

c. During standard one-port calibration (such as was done in the very first lab), the network analyzer uses three "perfect" standards -- an open circuit, a short circuit, and a matched load. For full two-port calibration, it uses these standards on BOTH arms, plus uses a direct connection between the two arms (connecting the two arms directly together) Using what you know about ABCD matrices, explain what the network analyzer is doing and how the calibration is done (you do NOT need to do any of the calculations). How many unknowns are there? And how many equations?

ECE 6180 Midterm I

Name ___________________________

Problem 1 ________ / 33 points

Problem 2 ________ / 33 points

Problem 3 ________ / 33 points

+ 1 point

Total ________ / 100 points