How does a shorted transmission line appear to a generator whose length is a quarter of the wavelength? - Avionics MCQ

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

How does a shorted transmission line appear to a generator whose length is a quarter of the wavelength?

A)

RC tuned circuit

B)

Short circuited line

C)

Very low impedance

D)

Very high impedance

Correct Answer : Very high impedance

Explanation : At the load end of the shorted one quarter wavelength line, voltage is zero and current is maximum. But one-quarter wavelength back, at the generator, the voltage is maximum and the current is zero. To the generator, the line appears as an open circuit, or at least very high impedance.

Recently Updated in Avionics Questions

The special transmission lines constructed on PCBs to act as tuned circuits is called as?

A)

Loop lines

B)

Stripline

C)

Printed lines

D)

Transmission lines

Correct Answer : Option (B) : Stripline

Explanation : At UHF and microwave frequencies the values of inductance and capacitance become so small that it is difficult to realize them physically with standard coils and capacitors. Special transmission lines constructed with copper patterns on a printed circuit board (PCB), called microstrip or stripline, can be used as tuned circuits, filters, phase shifters, reactive components, and impedance-matching circuits at these high frequencies.

The impedance of a line is zero when ________

A)

It acts as inductor

B)

It acts as capacitor

C)

It acts as a resistor

D)

Series resonant circuit

Correct Answer : Option (D) : Series resonant circuit

Explanation : If the line acts as a series resonant circuit, its impedance is zero. If the line is of such a length that it acts as a parallel resonant circuit, its impedance is near infinity. If the line is some intermediate length, it is reactive.

When does an open transmission line look like an inductor to the generator?

A)

Length is one quarter wavelength

B)

Length is more the one half of the wavelength

C)

Length is between one quarter and one half of wavelength

D)

At all times

Correct Answer : Option (C) : Length is between one quarter and one half of wavelength

Explanation : If the open transmission line is less than one-quarter wavelength, the generator sees a capacitance. If the line is between one-quarter and one-half wavelength, the generator sees an inductance. These characteristics repeat for lines that are some multiple of one-quarter or one-half wavelengths.

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