Antennas Multiple Choice Questions on “Types”.
1. Which of the following type does the slot antenna belongs?
a) Aperture Type
b) Wire Type
c) Lens Type
d) Reflector Type
Answer: a
Clarification: Slot antenna belongs to the aperture antenna and operates at 300MHz to 30GHz. Dipole is an example of Wire type. Reflector type example is Parabolic. Lens type: Convex-plane.
2. In which of the following band the slot antenna operates?
a) UHF and SHF
b) SHF and VLF
c) VLF and MF
d) UHF and EHF
Answer: a
Clarification: Slot antenna operates in the range of 300MHz to 30GHz.
VLF-3 KHz – 30 KHz
MF- 300 KHz – 3MHz
UHF- 300 MHz-3GHz
SHF- 3 GHz -30 GHz
EHF- 30GHz-300GHz
So slot antenna operates at UHF and SHF range.
3. Which of the following antenna is obtained by removing a small area of metal from an infinite ground plane?
a) Slot antenna
b) Plane reflector
c) Dipole
d) Yagi-Uda
Answer: a
Clarification: Slot antenna belongs to the aperture antenna and operates at 300MHz to 30GHz. It is obtained by removing a small area of metal from an infinite ground plane.
4. What is the principle used in slot antennas?
a) Babinet’s principle
b) Archimedes principle
c) Geo-Optics
d) Image Theory
Answer: a
Clarification: Babinet’s principle is used in slot antenna. It relates the fields obtained directly by slot antenna with corresponding complementary strip dipoles. It relates transmission/reception characteristics like radiation pattern, gain, and input impedance of those two complementary antennas. Geo-optics is used in reflectors and Image theory in Corner reflectors.
5. Microstrip slot antennas are complementary to the Microstrip dipole antennas
a) True
b) False
Answer: a
Clarification: Microstrip slot antenna uses a Babinet’s principle. It relates transmission/reception characteristics like radiation pattern, gain, and input impedance of those two complementary antennas. Slot antenna belongs to the aperture antenna and operates at 300MHz to 30GHz.
6. Which of the following slot antenna radiation can be modified electronically by tunable capacitor?
a) Annular slot antenna
b) Tapered slot antenna
c) Both annular and tapered
d) Neither annular nor tapered
Answer: a
Clarification: Annular slot antenna radiation can be tuned electronically by using tunable capacitor and is used for mobile communications. Tapered slot produces end-fire radiation.
7. Which of the following type of slot antenna gives good end-fire radiation?
a) Annular slot antenna
b) Tapered slot antenna
c) All slot antennas gives good end-fire radiation
d) None of slot antenna gives good end-fire radiation
Answer: b
Clarification: Microstrip slot antennas are usually poor end-fire radiators except tapered slot antenna. Slot antenna belongs to the aperture antenna and operates at 300MHz to 30GHz.
8. What is the impedance of 2- element slot antenna with single slot antenna resistance =500Ω?
a) 125Ω
b) 500Ω
c) 1000Ω
d) 250Ω
Answer: a
Clarification: impedance of N-element slot antenna (Z_{in,N} = frac{Z_{slot}}{N^2} )
Given N=2, Now (Z_{in,N} = frac{Z_{slot}}{N^2} = frac{500}{4} = 125Omega )
9. Which of the following cannot be used to reduce the radiation resistance in slot antenna for a given slot size?
a) Center feed
b) Off-center feed
c) Inclined slot
d) Stub tuning
Answer: a
Clarification: A center feed slot has high radiation resistance and requires a matching network to match the antenna. Off-center, Inclined slot and stub-tuning are some techniques used to reduce the radiation resistance of slot antenna.
10. The bi-directional radiation disadvantage in slot antenna can be rectified with metallic cavity
a) True
b) False
Answer: a
Clarification: The slot antenna has low cross polarization compared to patch antenna but its disadvantage is that it has bi-directional radiation which is corrected with the metallic cavity or reflector.