This set of Antennas Multiple Choice Questions & Answers (MCQs) focuses on “Feed Methods”.
1. Which of the following is used to excite to radiate the antenna?
a) Feed line
b) Ground plane
c) Patch
d) Substrate
View Answer
Explanation: The feedline is sued to excite to radiate the antenna in direct or indirect way. There are mainly four different types of feeding in Microstrip antenna: Microstrip line feed, coaxial probe, aperture coupling, proximity coupling.
2. Which of the following fed line is connected to patch just like a conducting strip?
a) Microstrip line feed
b) Coaxial feed
c) Aperture coupling
d) Proximity Coupling
View Answer
Explanation: Microstrip line feed acts as an extent to patch and is connected to patch just like a conducting strip. In coaxial feed, inner conductor is attached to patch and outer conductor to ground plane. In Aperture coupling, two different substrates are separated by ground plane. In Proximity coupling, the length of stub and length to width ratio of patch controls the match.
3. Which of the following feed line contains two different substrates separated by a ground plane?
a) Microstrip line feed
b) Coaxial feed
c) Aperture coupling
d) Proximity Coupling
View Answer
Explanation: In Aperture coupling, the ground plane separates two different substrates. In Microstripline feed, the feed is connected to the patch like a conducting strip. The coaxial feed consists an inner conductor attached to the patch and ground plane to the outer conductor. The length of stub and length to width ratio of patch is used for matching in proximity coupling.
4. Which of the following is true regarding the coaxial coupling feed in Microstrip antenna?
a) Inner conductor is connected to patch and outer conductor to ground plane
b) Outer conductor is connected to patch and inner conductor to ground plane
c) It is connected to patch just like a conducting strip
d) It contains two different substrates separated by a ground plane
View Answer
Explanation: A coaxial feed consists of inner and outer conductors to which the patch and ground planes are attached respectively. In a Microstrip feed line the patch is attached to the feed like a conducting strip. Different substrates are used in aperture coupling.
5. Which of the following feed line uses the length of stub and L/W ratio to control the match?
a) Microstrip line feed
b) Coaxial feed
c) Aperture coupling
d) Proximity Coupling
View Answer
Explanation: In Proximity coupling, the length of stub and length to width ratio of patch controls the match. Microstrip line feed acts as an extent to patch and is connected to patch just like a conducting strip. In coaxial feed, inner conductor is attached to patch and outer conductor to ground plane. In Aperture coupling, ground plane separates the different substrates.
6. Which of the following is the disadvantage of Microstrip line feeding?
a) Spurious feed radiation increases with increase in substrate thickness
b) Spurious feed radiation decreases with increase in substrate thickness
c) There is no Bandwidth limit
d) Low spurious radiation
View Answer
Explanation: Microstrip line feed acts as an extent to patch and is connected to patch just like a conducting strip. So the substrate thickness may increases leading to the increase in spurious radiation and this limits the bandwidth.
7. Which of the following is the disadvantage of the coaxial feeding?
a) Fabrication is very difficult
b) Low spurious radiation
c) Narrow Bandwidth
d) No generation of higher order modes
View Answer
Explanation: In coaxial feed, inner conductor is attached to patch and outer conductor to ground plane. Coaxial feeding fabrication is simple and has low spurious radiation which is its advantage. Due to asymmetries, higher modes are generated and produces cross polarization radiation.
8. Which of the following allows independent optimization of feed mechanism?
a) Microstrip line feed
b) Coaxial feed
c) Aperture coupling
d) Proximity Coupling
View Answer
Explanation: In Aperture coupling, two different substrates are separated by ground plane. This type of arrangement optimizes feed mechanism and radiating element.In Proximity coupling, the length of stub and length to width ratio of patch controls the match. Microstrip line feed acts as an extent to patch and is connected to patch just like a conducting strip. In coaxial feed, inner conductor is attached to patch and outer conductor to ground plane.
9. Which of the following feeding has largest bandwidth?
a) Microstrip line feed
b) Coaxial feed
c) Aperture coupling
d) Proximity Coupling
View Answer
Explanation: Proximity coupling feed provides largest bandwidth. Microstrip line feed limits the bandwidth due to increase in substrate thickness. Coaxial feed has narrow bandwidth.
10. In aperture coupling, ground plane is used to minimize the inference due to spurious radiation.
a) True
b) False
View Answer
Explanation: In Aperture coupling, two different substrates are separated by ground plane. This type of arrangement optimizes feed mechanism and radiating element. The ground plane is between the substrates and isolates feed from the radiating element and minimizes the interference due to spurious radiation.
Sanfoundry Global Education & Learning Series – Antennas.
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