This set of Antennas Multiple Choice Questions & Answers (MCQs) focuses on “Design – 1”.
1. If the flare angle of the horn increases, then its beam width ______
a) Decreases
b) Increases
c) Depends on aperture of horn
d) Independent of flare angle
View Answer
Explanation: The beam width of the horn antenna increases as the flare angle increases. The reflections are decreases as the flare angle increases. But at 900, the antenna approximates to an open end waveguide and its gain decreases.
2. Find the width of aperture of the E-plane horn operating at frequency 800MHz with the slant length 5cm?
a) 1.936 cm
b) 19.36 cm
c) 0.194 cm
d) 1.936 m
View Answer
Explanation: Aperture width \( = \sqrt{2λL}=\sqrt{\frac{2c}{f} L}=\sqrt{\frac{2×3×10^{10}}{800×10^6}×5}=19.36 cm\)
3. Find the aperture width of the H-plane horn operating at frequency 900MHz with the slant length 5cm?
a) 2.236 cm
b) 22.36 cm
c) 0.224 cm
d) 2.236 m
View Answer
Explanation: Aperture width \( = \sqrt{3λL}=\sqrt{\frac{3c}{f} L}=\sqrt{\frac{3×3×10^{10}}{900×10^6}×5}=22.36 cm\)
4. Find the diameter of the conical horn operating at frequency 900MHz with the slant length 1.5cm?
a) 1.224 cm
b) 12.24 cm
c) 0.122 cm
d) 1.224 m
View Answer
Explanation: Diameter \( = \sqrt{3λL}=\sqrt{\frac{3c}{f} L}=\sqrt{\frac{3×3×10^10}{900×10^6}×1.5}=12.24 cm \)
5. Find the directivity of a pyramidal horn antenna with E-plane aperture width 10λ and H-plane aperture width 15λ?
a) 30.15dB
b) 30.51dB
c) 3.051dB
d) 35.01dB
View Answer
Explanation: Directivity \( = 10log_{10}\frac{7.5A_e}{λ^2} = 10log_{10}\frac{7.5×10λ×15λ}{λ^2} =30.51dB
\)
6. Find the length of the E-plane horn with aperture 12λ and path travel difference 0.4λ?
a) 3.5 λ
b) 45 λ
c) 54 λ
d) 9 λ
View Answer
Explanation: Length of the E-plane horn \(ρ =\frac{h^2}{8δ}=\frac{(12λ)^2}{8×0.4λ}=45 λ\)
7. Find the flare angle of the H-plane horn with aperture 12λ and path travel difference 0.4λ?
a) 15.18°
b) 7.09°
c) 30.18°
d) 1.518°
View Answer
Explanation: Length of the H-plane horn \(ρ =\frac{h^2}{8δ}=\frac{(12λ)^2}{8×0.4λ}=45 λ\)
Flare angle of the H-plane horn = \(2tan^{-1}\frac{h}{2ρ}=2×tan^{-1}\frac{12λ}{2×45λ}=15.18°\)
8. Which of the following is the correct form of design equations of a horn antenna?
a) Length \(ρ=\frac{h^2}{8δ}, flare\, angle=2tan^{-1}\frac{h}{2ρ}\)
b) Length \(ρ=\frac{h^2}{4δ}, flare\, angle=2tan^{-1}\frac{h}{2ρ}\)
c) Length \(ρ=\frac{h^2}{4δ}, flare\, angle=tan^{-1}\frac{h}{2ρ}\)
d) Length \(ρ=\frac{h^2}{8δ}, flare\, angle=tan^{-1}\frac{h}{2ρ}\)
View Answer
Explanation: Design equations of a horn antenna are:
Length \(ρ=\frac{h^2}{8δ},flare\, angle\, θ=2 tan^{-1}\frac{h}{2ρ}\)
9. What are the length and the flare angle of the H-plane horn antenna with aperture 10 λ and path difference δ=0.2λ?
a) Length=31.8λ,flare angle=4.15°
b) Length=62.5λ,flare angle=9.14°
c) Length=31.8λ,flare angle=9.14°
d) Length=62.5λ,flare angle=4.15°
View Answer
Explanation: Length of the H-plane horn \(ρ=\frac{h^2}{8δ}=\frac{(10λ)^2}{8×0.2λ}=62.5λ\)
Flare angle of the H-plane horn \(= 2tan^{-1}\frac{h}{2ρ}=2×tan^{-1}\frac{10λ}{2×62.5λ}=9.14° \)
10. Find the optimum aperture angle for H-plane horn with aperture 12λ and path travel difference 0.4λ?
a) 75.9°
b) 1.59°
c) 7.59°
d) 15.18°
View Answer
Explanation: Optimum aperture angle of the H-plane horn = \(tan^{-1}\frac{h}{2ρ}=tan^{-1}\frac{12λ}{2×45λ}=7.59°\)
Sanfoundry Global Education & Learning Series – Antennas.
To practice all areas of Antennas, here is complete set of 1000+ Multiple Choice Questions and Answers.
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