# Circular Waveguide MCQ’s

This set of RF & Microwave Circuit Design Multiple Choice Questions & Answers (MCQs) focuses on “Circular Waveguide”.

1. Bessel’s differential equation for a circular waveguide is:
a) ρ2(d2R/ dρ2) + ρ(dR/dρ) + (ρ2kC2– n2) R=0
b) n2(d2R/ dρ2) + n(dR/dρ) + (ρ2kC2– n2) R=0
c) d2R/ dρ2 + dR/dρ + (ρ2kC2– n2) R=0
d) None of the mentioned

2. The lowest mode of TE mode propagation in a circular waveguide is:
a) TE10 mode
b) TE00 mode
c) TE01 mode
d) TE11 mode

3. In TE mode of a circular waveguide, EZ=0. The wave equation is:
a) ∇2HZ+k2HZ=0
b) ∇2HZ-k2HZ=0
c) ∇2HZ-HZ=0
d) ∇2HZ+HZ=0

4. What is the cutoff frequency for TE₁₁ mode in a circular waveguide of radius 2 cm with P’₁₁= 1.841?
a) 5.5 GHz
b) 4.3 GHz
c) 7.7 GHz
d) 8.1 GHz

5. For a circular waveguide in TM11 mode of propagation with inner radius of 30mm, and the phase constant being equal to 0.3, then the wave impedance is equal to:
a) 0.16 Ω
b) 0.15 Ω
c) 0.5 Ω
d) 0.4 Ω

6. In TM mode, what is the first propagating mode?
a) TM01 mode
b) TM11 mode
c) TM12 mode
d) TM10 mode

7. In a circular waveguide, if the propagation is in TE21 mode with P21=3.054, with a diameter of 60 mm, then the cutoff frequency for the mode is:
a) 5.6 GHz
b) 6.4 GHz
c) 3.5 GHz
d) 4.8 GHz

8. For TM mode. The wave equation in cylindrical co ordinates is:
a) (∂2/∂ρ2+1/ρ ∂/∂ρ + 1/ρ2 (∂2/∂∅2 + kc2) =0
b) ∂2E2/∂ρ2 + 1/ρ ( ∂E/∂ρ)=0
c) ∂2E2/∂ρ2 + 1/ρ2 (∂2E2/∂∅2 ) = 0
d) None of the mentioned

9. For TM01 mode of propagation in a circular waveguide with P01=2.405, with the inner diameter of the circular waveguide being equal to 25 mm. What is the cut off frequency for this mode of propagation?
a) 2.8 GHz
b) 6 GHz
c) 3.06 GHz
d) 4 GHz.

10. The cutoff frequencies of the first two propagating modes of a Teflon on a filled circular waveguide with a=0.5 with ∈r=2.08 is:
a) 12.19 GHz, 15.92 GHz
b) 10 GHz, 12 GHz
c) 12 GHz, 15 GHz
d) 15 GHz, 12 GHz

11. If β is 0.3 for a circular wave guide operating in TM12 mode with P21=5.315, with the radius of the circular waveguide being equal to 25 mm, then the intrinsic impedance of the wave is:
a) 0.55 Ω
b) 0.4 Ω
c) 0.3 Ω
d) 1.2 Ω