GROL Antennas and Transmission Lines 3

Question 1

What is the approximate gain of a half-wave dipole antenna relative to an isotropic radiator?

Accepted Answer

2.15 dBi

Answer

A half-wave dipole concentrates radiation broadside to the element in a figure-eight pattern, yielding approximately 2.15 dBi gain over an isotropic (point) radiator.

Question 2

What is the primary advantage of a Yagi-Uda antenna for fixed point-to-point communication links?

Accepted Answer

It provides high directional gain toward a specific direction

Answer

A Yagi-Uda antenna uses a reflector, driven element, and one or more directors to focus radiated energy in a single direction, providing substantial gain.

Question 3

What determines the polarization of a transmitted radio wave?

Accepted Answer

The orientation of the electric field, determined by the physical orientation of the radiating element

Answer

Antenna polarization is defined by the orientation of the transmitted electric field vector, which corresponds to the physical orientation of the antenna element.

Question 4

What is the -3 dB beamwidth of a directional antenna?

Accepted Answer

The angular width between the two points on the main lobe where radiated power falls to half its peak value

Answer

The -3 dB beamwidth is measured between the two half-power points on either side of the main radiation lobe peak, indicating how tightly the antenna focuses its energy.

Question 5

What is the radiation resistance of a half-wave dipole antenna in free space?

Accepted Answer

73 ohms

Answer

A half-wave dipole in free space has a radiation resistance of approximately 73 ohms, which represents the resistive component of its feedpoint impedance accounting for radiated power.

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Antennas and Transmission Lines 3