1. Which of the following does not belong to the aperture antenna?
a) Half-Dipole
b) Horn Antenna
c) Waveguide antenna
d) Slot antenna
Explanation: Antenna with an aperture at the end is known as aperture antenna. Horn antenna, Waveguide antenna and slot antenna are examples of aperture antenna. Half-dipole is a wire antenna.
2. Which of the following principle is used for analysis of aperture antennas?
a) Equivalence principle
b) Friss Equation
c) Reflectivity
d) Diffraction
Explanation: Equivalence principle follows the uniqueness theorem. It provides a unique solution for the boundary conditions. So this is used in the analysis of the aperture antennas. Friss transmission is used to relate the distance and power radiation between the antennas. Reflectivity and diffraction are not the principles used for analysis of aperture antenna.
3. Equivalence Principle follows which of the following theorem?
a) Uniqueness Theorem
b) Poynting theorem
c) Friss Theorem
d) Gauss theorem
Explanation: Equivalence principle follows the uniqueness theorem. It provides a unique solution for the boundary conditions. Uniqueness theorem is defined from the pointing theorem. Friss transmission is used to relate the distance and power radiation between the antennas. Gauss theorem states that total electric flux enclosed by charge is equal to net positive charge.
4. Which of the following condition is true for the electric conductor equivalent?
a) Js=n×H=0;Ms=-n×E
b) Js=n×H;Ms=-n×E=0
c) Js=n×H≠0;Ms=-n×E
d) Js=n×H≠0;Ms=-n×E=0
Explanation:The equivalent surface currents Js, Ms radiates fields H, E respectively. The conditions for the electric conductor equivalent is Js=n×H=0;Ms=-n×E.
5. Which of the following condition is true for the magnetic conductor equivalent?
a) Js=n×H=0;Ms=-n×E
b) Js=n×H;Ms=-n×E=0
c) Js=n×H≠0;Ms=-n×E
d) Js=n×H≠0;Ms=-n×E=0
Explanation: The equivalent surface currents Js, Ms radiates fields H, E. The conditions for the electric conductor equivalent is Js=n×H;Ms=-n×E=0. This is one of the equivalence principle modes.
6. Equivalence principle is mainly used for far filed analysis of the antenna in outer region.
a) True
b) False
Explanation: Equivalence principle follows the uniqueness theorem. It provides a unique solution for the boundary conditions. So this is used in the far field analysis of the aperture antennas in the outer regions.
7. The gain of the aperture antenna increases with square of the frequency.
a) True
b) False
Explanation: One of the distinguishing features of the aperture antenna is the increase in gain with operating frequency. The gain of the aperture antenna increases with square of the frequency if its aperture efficiency is kept constant with respect to the frequency.
8. Huygens principle in mathematical form is referred to as equivalence principle for aperture antennas.
a) True
b) False
Explanation: The equivalence principle replaces the aperture antenna with surface currents and thereby fields. It is derived from the uniqueness theorem and provides a unique solution for the boundary conditions for the fields. This is mainly used for the far field analysis of the aperture antenna.
9. Which of the following type does horn antenna belongs?
a) Wire Antenna
b) Array Antenna
c) Aperture Antenna
d) Lens Antenna
Explanation: Horn antenna belongs to Aperture antenna. Flaring done is done at the aperture of the rectangular waveguide gives different types of horn antenna. Dipole belongs to Wire antenna. Yagi-Uda is an array antenna. Convex-plane is example for lens antenna.
10. Which of the following antenna is mainly used for broadband signals?
a) Marconi antenna
b) Horn antenna
c) Wire antenna
d) Yagi-Uda antenna
Explanation: Horn antenna is used for broadband signals due to its flared nature. It is used to properly match the waveguide to a large radiating aperture by shaping transition gradually. It is used in 300MHz to 30GHz frequency range.