Test: Types of Waveguides & Its Properties - Electronics and Communication Engineering (ECE) MCQ

Answer: c
Explanation: The waveguides use total internal reflection phenomenon to transmit the waves passing through it. Thus the acceptance angle and critical angle are important for effective transmission.

Answer: b
Explanation: The dominant mode is the mode which has the minimum frequency or maximum wavelength available for propagation of the waves

Answer: d
Explanation: The modes are calculated from the V number of the waveguides. It is given by M= V²/2.

Answer: c
Explanation: The circular or cylindrical waveguides use the Bessel function for the frequency calculation of a particular mode.

Answer: c
Explanation: The scattering matrix consists of the transmission coefficients in the main diagonal and the reflection coefficients in the opposite diagonal.

Answer: a
Explanation: The T, ABCD and S parameter models are used in the transmission line modelling. The h parameter is not used for the same.

Answer: b
Explanation: The parameters S₁₂ and S₂₁ are the reflection coefficients. For a matched line, the reflection coefficients are zero. Thus the parameters S₁₂ and S₂₁ are also zero.

Answer: a
Explanation: Generally, the waveguides are made of materials with low bulk resistivity like brass, copper, silver etc. But if the interior walls are properly plated, it is possible with poor conductivity materials too. It is even possible to make plastic waveguides.

Answer: a
Explanation: In a scattering matrix, the parameters S₁₁ and S₂₂ indicate the transmission coefficients and the parameters S₂₁ and S₁₂ indicate the reflection coefficients.

Answer: a
Explanation: The waveguides aid in effective transmission of the electromagnetic power from the source antenna to the destination antenna.

Answer: d
Explanation: Waveguides are employed for effective transmission, when the lines carry electromagnetic waves in the GHz range.

Answer: d
Explanation: The cut off frequency of the waveguide is 6 GHz. This is the frequency at which the waveguide will start to operate.

Answer: b
Explanation: In rectangular waveguide, the a parameter is the broad wall dimension of the waveguide and the b parameter is the side wall dimension of the waveguide. Always, a > b in a waveguide.

Answer: a
Explanation: The Bessel function is used in the circular waveguides. Normally J_n(ha) = 0. Here n is the order of the Bessel function.

Answer: b
Explanation: In air medium, the phase velocity is assumed to be the speed of light. For waveguides, the phase velocity is always greater than the speed of the light.

Answer: a
Explanation: In a waveguide, the phase velocity is greater than the velocity of light. Thus the group velocity will be less. This implies the group wavelength will be greater than the wavelength at any point.

Answer: d
Explanation: The group wavelength is given by λg = 2π/βg, where βg is the group wavelength of the wave. On substituting for βg = 6.28, we get group wavelength as unity.

Answer: c
Explanation: The phase velocity of a wave is given by Vp = ω/βg. on substituting for ω = 15 and βg = 2, we get phase velocity as 15/2 = 7.5 units.

Answer: c
Explanation: The relation between the modes and the V number is given by m = v²/2. Given that v = 20, we get m = 20²/2 = 200 modes

Answer: b
Explanation: The relation between the modes and the V number is given by m = v²/2. Given that m = 50, we get v² = 2 x 50 = 100. The V number is 10.