1. Which of the following antenna has the parallel slots along the inside surface of the horn?
a) E-plane horn
b) Pyramidal horn
c) Exponential horn
d) Corrugated horn
Explanation: A Corrugated horn has parallel slots or grooves which are small in size compared to the wavelength. These are present along the inside surface of the horn and are transverse to the axis.These corrugated antennas have wider bandwidths and minimizes the side lobes.
2. In which of the following antennas the separation of sides increases as a function of length?
a) Conical horn
b) Exponential tapered pyramidal horn
c) Pyramidal horn
d) Sectoral horn
Explanation: In exponentially tapered pyramidal horn, the transition region is gradually tapered exponentially to minimize the reflections. These are mainly used when reflections in the waveguide are critical.
3. If the walls of the circular waveguide are flared out, then it is called _____
a) Pyramidal horn
b) E-plane horn
c) H-plane horn
d) Conical horn
Explanation: In conical horn, the walls of the circular waveguide are flared out. For pyramidal horn, the walls of the rectangular waveguide are flared out in both directions.
4. If the all the walls of rectangular waveguide are flared out, then it is called ______
a) Pyramidal horn
b) Conical horn
c) E-plane horn
d) H-plane horn
Explanation: For pyramidal horn, all the walls of the rectangular waveguide are flared out. E-plane and H-plane are Sectoral horn antennas which are flared in only one direction.
5. HPBW of E-plane horn is (in degrees) _____
a) \(\frac{56λ}{h_e} \)
b) \(\frac{67λ}{h_e} \)
c) \(\frac{λ}{56h_e} \)
d) \(\frac{λ}{67h_e} \)
Explanation:HPBW of E-plane horn is \(\frac{56λ}{h_e} \) where he the aperture dimension of E-plane horn.
6. HPBW of H-plane horn is (in degrees) _____
a) \(\frac{56λ}{h_h} \)
b) \(\frac{67λ}{h_h} \)
c) \(\frac{λ}{56h_h} \)
d) \(\frac{λ}{67h_h} \)
Explanation: HPBW of H-plane horn is \(\frac{67λ}{h_h} \) where hh the aperture dimension of H-plane horn.
7. HPBW of E-plane horn with aperture dimension 10 λ in degrees is ____
a) 56
b) 67
c) 5.6
d) 6.7
Explanation: HPBW of E-plane horn is \(\frac{56λ}{h_e} = \frac{56λ}{10λ}=5.6\).
8. HPBW of H-plane horn with aperture dimension 10 λ in degrees is ____
a) 56
b) 67
c) 5.6
d) 6.7
Explanation: HPBW of H-plane horn is \(\frac{67λ}{h_h} = \frac{67λ}{10λ}=6.7\).
9. Physical area of a conical horn antenna of radius 5cm is____
a) 25π
b) 6.15π
c) 2.5π
d) 5
Explanation: Physical area of conical horn A=πr2=π×52=25π.
10. Flare angle of horn antenna when axial length l and path difference δ is given is _____
a) \(θ= 2 cos^{-1}\frac{l}{l+δ} \)
b) \(θ= cos^{-1}\frac{l}{l+δ} \)
c) \(θ= 2 cos^{-1}\frac{l}{l-δ} \)
d) \(θ= cos^{-1}\frac{l}{l-δ} \)
Explanation: Flare angle of horn antenna when axial length l and path difference d is given is
\(θ= 2 cos^{-1}\frac{l}{l+δ} \).