How would the graph of wavelength vs voltage look like if the transmission line is matched (neglect resistive loss)?

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

Constant

Linearly increasing

Linearly decreasing

Exponentially decreasing

Correct Answer : Constant

Explanation : If a voltmeter is moved down a matched line from the generator to load and the rms voltage values are plotted, the resulting wavelength versus voltage line will be flat.

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

Loop lines

Stripline

Printed lines

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 ________

It acts as inductor

It acts as capacitor

It acts as a resistor

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?

Length is one quarter wavelength

Length is more the one half of the wavelength

Length is between one quarter and one half of wavelength

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.