ECE 6130 / 5930

Midterm II

April 23, 1999

 

Name ___________________________________

 

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

 

 

  2. (33 points) AWR-12 rectangular waveguide has the dimensions a = 0.122cm , b = 0.061cm.

 

  1. What are the first three TE modes of operation and what are their cutoff frequencies (in GHz)?

    2.  

    Mode

    Fc (GHz)
       
       
       

     

     

     

     

     

     

     

     

  2. Write an expression for the electric field Ex and Ez components when you are above the cutoff frequency for the 2nd mode and below the cutoff frequency for the 3rd mode.

 

The 2nd mode is: TE_____ The 3rd mode is: TE ______.

 

Ex =

 

 

 

 

 

 

 

 

 

 

 

 

 

Ez =

 

 

 

 

 

c. A transmission line (NOT necessarily a waveguide) is carrying a wave in the x-direction. THIS IS DIFFERENT FROM THE z-direction you have worked with throughout this course. Mark an "X" in the box of each field component that could exist in each of the following modes:

 

Field Component

TEM

TE

TM

Ex

      

Ey

      

Ez

      

Hx

      

Hy

      
  2. (33 points) Design a stub filter to implement the following filter design at 6 GHz. The filter will be connected to 50 ohm input and output lines. You may use variables, or if you prefer to use numbers use normalized values L1=L2 = 2 and C1=C2 = 3.

    3.  

    Hint: Remember that you can always add a length of line on the ends of the filter without changing its response. You may have to do this more than once. When you do, please indicate.

     

     

     

     

  4. (33 points)

 

  1. A Wilkinson power divider is designed so that 1/3 of the power comes out of port W1 and 2/3 of the power comes out of port W2. The input signal at port W1 is V=1.0 sin w t . The Wilkinson power divider is connected to a quadrature coupler as shown below. What is the output voltage at port Q2?

Hint: the S-parameters for the Quadrature Coupler are

 

 

 

 

 

 

ECE 6130 / 5930 Midterm II

 

Name ___________________________________________

 

Problem 1 _______ / 33 points

 

Problem 2 _______ / 33 points

 

Problem 3 _______ / 33 points

 

Total _______ / 100 points

 

 

 

  2. (33 points)

 

a.