2. Antennas Flashcards
What determines an antenna’s resonant frequency?
Resonant frequency of an antenna is determined by the antenna element length.
Can an antenna’s resonant frequency be adjusted?
If so, how?
Yes
Antenna’s characteristic (resonant) frequency is electrically adjustable.
What does insertion of coils in an antenna element do?
Insertion of coils in an antenna element lowers the resonant frequency.
What does insertion of capacitors in an antenna element do?
Insertion of capacitors in an antenna element makes the resonant frequency higher.
How is an airborne HF communication system tuned?
Airborne HF communication systems have an antenna tuner in the antenna circuit. It adjusts the resonant frequency and performs impedance matching.
What do feed lines do?
Feed lines conduct radio frequency current with minimal loss.
It is used to connect a transmitter or receiver to an antenna
What types of antennas are used for VHF and UHF radio equipment?
Sleeve antennas, Brown antennas, and Yagi antennas are used for VHF and UHF radio equipment.
What type of antenna is a Yagi antenna?
A Yagi antenna is a directional antenna.
What should be considered when selecting an antenna?
An appropriate antenna should be selected in accordance with the type of radio service and operating frequency.
When does an antenna radiate and receive signals most efficiently?
An antenna radiates and receives signals most efficiently at its resonant frequency
What do antennas do?
Antennas convert radio frequency current into radio waves for transmission, and change waves to radio frequency current for reception.
When are coaxial cables used?
Coaxial cables are widely used on HF, VHF, and UHF.
When are waveguides used?
Waveguide is applied to the equipment of microwave range.
When would a half wavelength dipole antenna be used?
Half wavelength dipole antenna is often used for MF and HF range equipment
When are direction antennas often used?
Used for radar equipment
