Transmission Lines Concepts Quiz

Transmission Lines Exam Questions

• Part 1: Matching

  • For best matching, the reflection coefficient should be equal to zero.
  • The reflection coefficient should not be equal to one, infinity or a negative value

• Contributing Factors

  • The reflection coefficient depends on the propagation constant and characteristic impedance (Zo).
  • Incident voltage is affected by the propagation constant.
  • The incident current is affected by the transmission line's length.

• Open-Circuited Line Reflection Coefficient

  • An open-circuited line has a reflection coefficient of -1.

• Interference of Waves

  • Standing waves are created by the interference of incident and reflected waves that travel in opposite directions.

• Minimum Impedance

  • The minimum impedance in a transmission line is determined by the ratio of the minimum voltage to the maximum current (Vmin/Imax).

• Open and Short Circuits

  • In an open circuit configuration, the sum of incident voltage and reflected voltage is at a maximum value.
  • In a short circuit configuration, the sum of incident current and reflected current is maximum.

• Impedance at Line Termination

  • The impedance at the termination of a shorted line is undefined.

• Quarter-Wave Transmission Line Termination

  • The impedance of a quarter-wave transmission line terminated in an open circuit acts as a capacitor

• Half-Wavelength Transmission Line Termination

  • The impedance of half-wavelength transmission line terminated in an open circuit acts as a series resonant circuit

• λ/8 Transmission Line Termination

  • The impedance of a λ/8 transmission line terminated in an open circuit acts as a capacitor

• 3λ/8 Transmission Line Termination

  • The impedance of a 3λ/8 transmission line terminated in a short circuit acts as a parallel resonant circuit.

• Inductive and/or capacitive line

  • If the transmission line is purely inductive or capacitive, the minimum voltage(Vmin) will appear before Smax.

• Stub Matching

  • In a step-up quarter-wave transformer matching configuration, the load resistance (RL) is greater than the characteristic impedance (Zo).
  • The stub is placed away from the primary line.

• Smith Chart Usage

  • The first step when using a Smith chart is to draw the impedance circle.

• Microstrip Characteristics

  • Microscopic transmission lines are constructed with a high-grade printed circuit and have an insulating substrate.

• Reflection Coefficient Relationship

  • The relationship between incident and reflected voltage, and reflection coefficients, is determined by the characteristic impedance and the impedance of the load.

• Expressions for Reflection Coefficient

  • Not all expressions below represent the reflection coefficient;
  • Multiple expressions determine the reflection coefficient values.

• Determining First Voltage Maximum Position

  • The position of the first maximum voltage is determined by certain equations.