Electromagnetic Transmission Lines and Antennas

Questions and Answers

What is the phase relationship between the incident and reflected voltage waves in an open-ended transmission line with an ac signal applied?

In phase

180 degrees out of phase (correct)

45 degrees out of phase

90 degrees out of phase

What type of circuit does a series-resonant circuit act as when the frequency is above the generator frequency?

Open circuit

Capacitive circuit (correct)

Inductive circuit

Resistive circuit

What is the resultant of the incident and reflected voltage waves called?

Concentrated wave

Traveling wave

Standing wave (correct)

Algebraic wave

How is the value of the standing wave figured?

By algebraically adding the two waveforms Signup and view all the answers

What condition exists at the end of a shorted transmission line?

Maximum voltage and minimum current Signup and view all the answers

Which of the following transmission line sections can be used as a parallel-resonant circuit?

An open 1/4-wavelength section Signup and view all the answers

What is the phase relationship between the standing waves of voltage and current in an open-ended transmission line?

90 degrees out of phase Signup and view all the answers

Which of the following is NOT a characteristic of a resonant circuit?

None of the above Signup and view all the answers

What type of circuit appears as a very high resistance at resonance?

A parallel-resonant circuit Signup and view all the answers

What is the condition for a long transmission line where the characteristic impedance can be determined using the method of calculating the impedance of the entire line?

When the line is infinitely long Signup and view all the answers

When a transmission line is terminated in an inductive reactance, what phase shift takes place with respect to the current and voltage?

Both voltage and current are phase-shifted Signup and view all the answers

What is the term for a device used to radiate or receive electromagnetic wave energy?

Antenna Signup and view all the answers

What happens to the voltage along the length of a transmission line when it is not terminated in its characteristic impedance?

Standing waves of voltage and current form Signup and view all the answers

When a transmission line is terminated in a resistance greater than Z0, what is the condition at the end of the line?

The end of the line appears as an open circuit Signup and view all the answers

When should lumped values for transmission-line constants be used to calculate characteristic impedance?

When the line is short compared to one wavelength Signup and view all the answers

On a standing wave, what are the points of high current and voltage identified by?

Peaks Signup and view all the answers

What happens to the incident energy that is NOT transferred to the load when a transmission line is not terminated in its characteristic impedance?

It is returned along the transmission line Signup and view all the answers

Compared to a dc input, what relative amount of time is required for an ac input voltage to travel the length of the line?

Same Signup and view all the answers

What is the condition at the open end of a transmission line?

It reacts as if it were a short circuit Signup and view all the answers

When a transmission line is terminated in a resistance equal to Z0, what is the condition at the end of the line?

The end of the line appears as a matched load Signup and view all the answers

What is the condition for a long transmission line where the current flows indefinitely?

When the line is terminated in its characteristic impedance Signup and view all the answers

What is the method of determining the characteristic impedance of a transmission line by calculating the impedances at each end of the line?

Calculating the impedances of successive short sections Signup and view all the answers

What is the phase shift between the current and voltage on a transmission line terminated in an inductive reactance?

1/4 cycle Signup and view all the answers

What is the characteristic impedance of a long transmission line that is infinitely large?

Infinitely large Signup and view all the answers

Study Notes

Transmission Lines

A series-resonant circuit appears as a very high resistance at resonance.

Phase Shifts

When a transmission line is terminated in an inductive reactance, both voltage and current are phase-shifted.
In an open-ended transmission line with an ac signal applied, the phase relationship between the reflected voltage waves is 180 degrees out of phase.

Devices

A device used to radiate or receive electromagnetic wave energy is referred to as an antenna.
A shorted 1/4-wavelength section or an open 1/4-wavelength section of a transmission line can be used as a parallel-resonant circuit.

Transmission Line Conditions

When a transmission line is terminated in a resistance greater than Z0, the end of the line appears as an open circuit.
On an open-ended transmission line, the points of high current and voltage are identified by peaks.
On a standing wave, the points of high current and voltage are identified by peaks.

Characteristic Impedance

The characteristic impedance of a long transmission line may be determined by calculating the impedances at each end of the line or by adding the impedances of successive short sections.
Lumped values for transmission-line constants should be used to calculate characteristic impedance when the line is short compared to one wavelength.

Standing Waves

The resultant of the incident and reflected voltage waves is called the standing wave.
On an open-ended transmission line, standing waves of voltage and current form, where current flows indefinitely.
When a transmission line is not terminated in its characteristic impedance (Z0), the incident energy that is not transferred to the load is returned along the transmission line.

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Description

This quiz covers the concepts of transmission lines, phase shifts, and devices used in electromagnetic energy transmission, including antennas and shorted transmission lines.