Questions: Transmission lines

 

 

 

 

 

 

 

Question no. 1

A cable of length metres with a polyethylene dielectric, εr has a characteristic impedance of ohms and a loss of ohms/metre, and is left open circuit at its far end. Given a constant drive voltage versus frequency, at what lowest frequency will the current into its near end be a maximum?
Possible answers Choose



Answer A is:

Answer B is:

Answer C is:

Answer D is:

Review: Transmission line behaviour

Question no. 2

A multi-core screened cable has a screen diameter of cm and a total inner wiring diameter of cm with a PVC insulation, εr . Ignoring losses, what is the cable's internal common mode transmission line characteristic impedance?
Possible answers Choose



Answer A is:

Answer B is:

Answer C is:

Answer D is:

Review: Transmission line behaviour

Question no. 3

The same cable as in Q2 contains several wire pairs of 7/0.2mm (overall diameter including insulation of 1.2mm) with PVC insulation material, εr = 3. Ignoring losses, air gaps and coupling to other pairs, what is the differential mode transmission line impedance of each pair?

Possible answers Choose

Answer A is:

Answer B is:

Answer C is:

Answer D is:

Review: Transmission line behaviour

Question no. 4

What will happen (to a first order) to the differential pair Z0 if the wire pairs of Q3 are twisted?
Possible answers Choose

Answer A is:

Answer B is:

Answer C is:

Answer D is:

Review: Transmission line behaviour

Question no. 5

The standard Ethernet interface has an RC network between the centre tap of the transformer and the ground reference. What is its purpose?
Possible answers Choose

Answer A is:

Answer B is:

Answer C is:

Answer D is:

Review: Balanced interfaces (Ethernet)