ECE 6180 Midterm II March 23, 2001

Name _____________________________

You may use your calculator and portfolio. Read the problems CAREFULLY. Good luck and do well!

1. (33 points) Design a Wilkinson power divider for 5:1 power splitting (1/6 of the power comes out of arm 1, and the other 5/6 comes out of arm 2).

(a) Specify the following impedances:

Zo = 50 W

Z_o2 = ________ W

Z_o3 = ________ W

(b) Be sure to match all three arms to 50 W. Specify the following impedances:

Z_o4 = ________ W

Z_o5 = ________ W

(c) THINKING part of this problem (you may prefer to come back to this later)

Information on the microstripline:

Frequency = 2.5 GHz

Substrate e_r = 2.2 and s=0

W/d (width/thickness of substrate) = 3 for a 50 W line.

Assume W/d for a line of Z_k impedance is: W/d = (3.0) 50 W / Z_k

(a 100 W line is approximately half the width of a 50 W line).

Hint: The effective dielectric constant of the microstripline is:

What is the length IN METERS of

L2 = __________ meters

L4 = __________ meters

2. (33 points) Design a high pass LUMPED ELEMENT filter with cutoff frequency of 3 GHz. At 1 GHz, the attenuation should be at least 20 dB. The filter should be matched to 50 W lines and have minimal ripple. SKETCH your filter and SPECIFY all L and C values.

3. (33 points) A 4^th order maximally flat LP filter has g₁ = g₄ = 0.76, g₂ = g₃ = 1.8 and is matched on both ends. It is implemented:

(a) Apply only ONE Kuroda identity to determine the impedance of the first (left-most) stub of a stub filter. How long is this stub?

Zstub = ___________ Length of stub = __________ l

(b) SHOW (with pictures) that you know how to apply the remaining Kuroda identities to convert L₃ to a parallel stub. You do NOT need to do any calculations or show any equations. Just sketch the steps that would be done.

ECE 6180 Midterm II

Name __________________________

Problem 1 _______ / 33 points

Problem 2 _______ / 33 points

Problem3 _______ / 33 points

+ 1 point

Total _______ / 100 points