3001comms Flashcards
antenna is not grounded at one end?
Dipole
…………… polarization is employed in FM broadcasting
Horizontal
…………… polarization is employed in AM broadcasting.
Vertical
An energy which radiates in the form of radio waves; infrared waves; light waves; x-rays; etc.
Electromagnetic
…………. is an antenna made up of a number of full wavelengths.
Long wire
When antennas are closed to the ground; ………….. polarization is ideal.
vertically polarized
makes an antenna physically long but electrically short.
Adding C in series
antennas is best excited from a waveguide
Horn
very useful as a multiband HF receiving antenna.
Log-periodic
An ungrounded antenna near the ground acts s
antenna array
Good grounding is important for
vertical antennas
ratio of the maximum radiation intensity to the average radiation intensity?
Directivity gain
………….. is the angle between the half-power radiation points.
Beamwidth
What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?
increased
What is the polarization of a discone antenna?
Vertical
When speaking of antennas; ……….. is a section which would be a complete antenna by itself
bay
range of frequencies are most omnidirectional horizontally polarized antennas used?
VHF; UHF
If the current ratios of the two or more elements must be held 5% and the phase angle to 3 degrees; the antenna is called a
critical phased array
non-resonant antenna
Rhombic antenna
Very low signal strength in antenna.
Null
………… is the measurement of a unilateral antenna properties of directivity
Beamwidth
In testing transmitter to prevent interfering with other stations; which type of antenna must be used?
Dummy antenna
The best solution of fading is ………….
space diversity
…………. is the amount of uncertainty in a system of symbols.
Entropy
Top loading is used in an antenna in order to increase its …………….
effective height
A horizontal antenna is ……………
horizontally polarized
All elements in a beam ………… antennas are in line.
collinear
…………….. is the antenna with a number of half-wave antenna on it.
Antenna array
antenna radiates an omnidirectional pattern in the horizontal plane with vertical polarization?
Marconi antenna
An antenna with very high gain and very narrow beamwidth.
Parabolic dish antenna
………….. is the horizontal pointing angle of an antenna.
Azimuth
Discone radiation pattern is …………..
omnidirectional
………….. is an open-ended slot antenna.
Notch antenna
radiation characteristic of a dipole antenna
Bidirectional
antenna with unity gain
Isotropic
An antenna which is one-tenth wavelength long.
Elementary doublet
The antenna radiates ………. polarized waves when the transmitter antenna is horizontally installed.
horizontally
Comparing the signal strength arriving at the driven element from the desired direction to the signal strength reaching the driver from the opposite direction.
Front-to-back ratio
……………. of an antenna is a measure of how the antenna concentrates its radiated power in a given direction.
Gain
Shortening effect of an antenna that makes it appear as if it were 5% longer
End effect
Actual height of antenna should be at least
quarter wavelength
…………… is an antenna array which is highly directional at right angles to the plane of the array?
Broadside array
The directivity pattern of an isotropic radiator is
sphere
A theoretical reference antenna that provides a comparison for antenna measurements.
isotropic radiator
Increasing the electrical length of an antenna means
add an inductor in series
