Question

The propagation constant of a wave is also known as its
A. wavelength
B. frequency
C. wave number
D. angular wave number

Answer 1

Hint: An electromagnetic wave is propagating in a sinusoidal manner. The amount of the variation in the amplitude and phase per unit distance is referred to as the propagation constant. It is abbreviated by the Greek letter $\gamma$ .

Complete step-by-step answer:
First of all let us discuss the propagation constant in detail. The propagation constant of an electromagnetic wave which is a sinusoidal wave in general is given as the amount of the variation occurred to the amplitude and phase of the wave as it is propagating in a certain direction. The quantity which is being calculated will be the voltage, the current in a circuit, or a field vector such as electric field strength or flux density generally. Its unit is given as the radians per metre. The equation of the propagation constant can be written as,
$\gamma ={\displaystyle \frac{2\pi }{\lambda }}$
Where $\lambda$ be the wavelength of the electromagnetic wave.
It is also called an angular wave number in general.

So, the correct answer is “Option D”.

Note: The term propagation constant or angular wavenumber is applicable in the case of filters and other two-port networks helpful for signal processing. In such cases, even though the attenuation and phase coefficients are shown in the radians per network section rather than per unit length. The propagation constant is a very helpful idea in filter design which is undoubtedly using a cascaded section topology. In this cascaded topology, the propagation constant, attenuation constant and phase constant of each of the sections will be added simply in order to calculate the total propagation constant.