Horn Antenna Questions and Answers – Design – 1

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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

Answer: b
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.
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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

Answer: b
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

Answer: b
Explanation: Aperture width \( = \sqrt{3λL}=\sqrt{\frac{3c}{f} L}=\sqrt{\frac{3×3×10^{10}}{900×10^6}×5}=22.36 cm\)
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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

Answer: b
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

Answer: a
Explanation: Directivity \( = 10log_{10}\frac{7.5A_e}{λ^2} = 10log_{10}\frac{7.5×10λ×15λ}{λ^2} =30.51dB
\)
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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

Answer: b
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

Answer: a
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 = \(2tan^{-1}⁡\frac{h}{2ρ}=2×tan^{-1}⁡\frac{12λ}{2×45λ}=15.18°\)
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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

Answer: a
Explanation: Design equations of a horn antenna are:
Length \(ρ=\frac{h^2}{8δ},flare\, angle\, θ=2 tan^{-1}⁡\frac{h}{2ρ}\)
Find the form of design equations of a horn antenna from the given diagram

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

Answer: b
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 \(= 2tan^{-1}⁡\frac{h}{2ρ}=2×tan^{-1}⁡\frac{10λ}{2×62.5λ}=9.14° \)
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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

Answer: c
Explanation: Optimum aperture angle of the H-plane horn = \(tan^{-1}⁡\frac{h}{2ρ}=tan^{-1}⁡\frac{12λ}{2×45λ}=7.59°\)

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter