Pleas explain why answer was chosen

QUESTION 17:The beam width of a signal transmitted from a directional antenna will decrease as the transmission frequency increases.

True False

QUESTION 18:Link margin is the difference in decibels between the actual power received, and the receivers specified receiver sensitivity.

True False

QUESTION 19:When microwave communication systems are used, it is important to ensure line-of-site (LOS) throughout the Fresnel zone.

True False

QUESTION 20:Polarization of an electromagnetic wave (EM) is determined by the polarization of the electrical field (i.e., not the magnetic field)

True False