Question: Define the terms w.r.t wave guide: a) group velocity b) phase velocity c) Cut-off frequency d) Guided wavelength of waveguide e) Cut off wavelength
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Subject: Advance Communication System

Difficulty: Low

Marks: 4 Marks

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modified 11 weeks ago by gravatar for Ankit Pandey Ankit Pandey ♦♦ 10 written 3 months ago by gravatar for Yashbeer Yashbeer ♦♦ 130
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Phase velocity: Phase velocity is defined as the rate at which the wave changes its phase in terms of the guide wavelength.

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The phase velocity is the velocity with which the wave changes phase in a direction parallel to the conducting surface.

The phase velocity is given by equation

$v_p$ = $\frac{v_c}{\sqrt{1- ({\frac{\lambda}{{\lambda}_c}})^2}}$

Where

Vc is velocity of light.

$\lambda$ is free space wavelength

$\lambda_o$ is cutoff wavelength

Group velocity: Group velocity is defined as the rate at which the wave propagates through waveguide .

Group velocity is given by equation

$v_g$ = $v_c{\sqrt{1- ({\frac{\lambda}{{\lambda}_c}})^2}}$

Where

Vc is velocity of light.

$\lambda$ is free space wavelength

$\lambda o$ is cutoff wavelength

The group velocity is also can be defined as the velocity of energy flow in the waveguide system.

Cut-off frequency: It is the frequency of the signal above which propagation of waves occur.

$f_c = \frac{c}{2}{\sqrt{({\frac{m}{a})^2}+ ({\frac{n}{b}})^2}}$

Guided wavelength of waveguide: It is defined as the distance travelled by the wave in order to undergo a phase shift of 2π radians along the waveguide.

$\lambda_g$ = $\frac{\lambda}{\sqrt{1+ ({\frac{\lambda}{{\lambda}_c}})^2}}$

Cut off wavelength: Cut-off wavelength for a parallel plane waveguide where only side walls are present i.e. only the a dimension is present,and it is given by,

$\lambda_c$ = $\frac{2a}{m}$

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modified 11 weeks ago  • written 12 weeks ago by gravatar for Ankit Pandey Ankit Pandey ♦♦ 10
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