ECE 5930 Midterm II

April 21, 2000

Name ___________________________________

You may use your calculator and portfolio, but no textbook.

Time: 1 hour

Remember to show what you know. If you get bogged down, or think you need information that is not here, make some assumptions, tell me what they are and why you chose them, and continue on.

Write and explain what you are doing, so I can give you partial credit.

There are FOUR problems on this exam.

Problem 1 = 33 points

Problem 2 = 10 points

Problem 3 = 32 points

Problem 4 = 25 points

1. (33 points) Design a T-junction power divider and associated matching networks for a set of transmitting antennas shown below. One antenna needs to transmit to a nearby receiver, so it only needs 1/3 of the voltage. The other antenna needs to transmit to a distant receiver, so it needs 2/3 of the voltage. The antennas are arranged so that you are NOT concerned with the field from one antenna being received from the other antenna.

(a)

Define the input impedance and electrical length (in terms of wavelength) of the microstriplines and the magnitudes of any discrete parts.

(b) Sketch the power divider. Accurately show which microstriplines are thinner than others.

2. (10 points)

Design a lumped element high pass filter with a cutoff frequency of 2 GHz and at least 20 dB of attenuation at 3 GHz. The maximum allowable ripple is 0.5 dB. Specify the capacitor and inductor values, and sketch the filter.

Name ______________________________________

Please Redo Problem 3 on the exam. Take 20 minutes. You may use your portfolio.

Return it to Dr. Furse

3. (32 points) A lumped element matching network is shown below. Demonstrate that you understand how to convert this to a microstrip stub filter design. Match the filter to 50 ohm input and output lines.

(a) Demonstrate how to do the numerical values of ONE Kuroda conversion (hence, only one capacitor value is specified)

(b) Demonstrate how to convert the lumped element network to a form that you can convert to microstripline stubs.

(c) Demonstrate how to convert this form to a stub filter. Sketch the filter and indicate everything that you know about the lengths and widths of these lines.

4. (25 points)

(a) If a quadrature coupler has the following input voltages, what is the output voltage on port 4? (You can set this up as an equation but not solve it to save time.)

(b) Does the result change when V1 is changed to 1000 Ð 30°Volts? Explain why or why not?

V1 = 1 Ð 30° Volts

V2 = 2 Ð 60° Volts

V3 = 3 Ð 90° Volts

V4 = 4 Ð 120° Volts

ECE 6130 Midterm II

Name ___________________________________________

Problem 1 _______ / 33 points

Problem 2 _______ / 10 points

Problem 3 _______/ 32 points

Problem 4 _______ / 25 points

Total _______ / 100 points

1. (33 points)

a.