Chapter 2, Antennas Flashcards
An isotropic radiator will radiate
Uniformly in all directions
Another name for a quarter-wave vertical
antenna is
A Marconi antenna
A full-wave dipole fed at the center must be
Current fed
The radiation efficiency of an antenna
Decreases with antenna loss resistance
A vertical quarter-wave antenna will have a polar diagram in the horizontal plane which is
Omnidirectional
Which one of the following gives the
approximate length of a half-wave dipole for use at 300 MHz?
50 cm
A standing wave ratio of 1:1 indicates
That there will be no reflected power
Which one of the following antenna types
would be most suitable for a fixed long
distance HF communications link?
A three-element horizontal Yagi
When two antennas are vertically stacked the combination will have
Increased gain and unchanged beamwidth
The characteristic impedance of a coaxial
cable depends on
The ratio of inductance to capacitance
The attenuation of an RF signal in a coaxial cable
Increases with frequency
If a transmission line is perfectly matched to an aerial load it will
It appears to be infinitely long
The characteristic impedance of an RF coaxial cable is
Usually between 50 and 75 Ω
The beamwidth of an antenna is measured
Between the 70% power points
