Antennas and Feed Lines Flashcards
Which of the following describes a simple dipole oriented parallel to the Earth’s surface? (T9A03)
A horizontally polarized antenna
In which direction does a half-wave dipole antenna radiate the strongest signal? (T9A10)
Broadside to the antenna
What is the approximate length, in inches, of a half-wavelength 6 meter dipole antenna? (T9A09)
112 (one half wavelength is 3m. 3m x 39.4 in/m =118.2. [antenna is about 5% shorter] 118.2 x .95 = 112
How would you change a dipole antenna to make it resonant on a higher frequency? (T9A05)
shorten it
What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? (T9A08)
19 (Wavelength of 146 MHz is approximately 2m. 1/4 x 2 = .5 *** .5 m x 39.4 in/m = 19.7 in. ** 19.7 in. x .95 = 19 in
Which of the following describes a type of antenna loading? (T9A02)
Inserting an inductor in the radiating portion of the antenna to make it electrically longer
What is a beam antenna? (T9A01)
An antenna that concentrates signals in one direction
What type of antennas are the quad, Yagi, and dish? (T9A06)
Directional Antennas
What is the gain of an antenna? (T9A11)
The increase in signal strength in a specified direction compared to a reference antenna
What is a disadvantage of the “rubber duck” antenna supplied with most handheld radio transceivers when compared to a full-sized quarter-wave antenna? (T9A04)
It does not transmit or receive as effectively
What is a disadvantage of using a handheld VHF transceiver, with its integral antenna, inside a vehicle? (T9A07)
Signals might not propagate well due to the shielding effect of the vehicle
What is an advantage of using a properly mounted 5/8 wavelength antenna for VHF or UHF mobile service? (T9A12)
It has a lower radiation angle and more gain than a 1/4 wavelength antenna
