What describes an isotropic antenna?

- A grounded antenna used to measure earth conductivity
- A horizontally polarized antenna used to compare Yagi antennas
- A theoretical antenna used as a reference for antenna gain
- A spacecraft antenna used to direct signals toward the earth

What antenna has no gain in any direction?

Why would one need to know the feed point impedance of an antenna?

- To match impedances in order to minimize standing wave ratio on the transmission line
- To measure the near-field radiation density from a transmitting antenna
- To calculate the front-to-side ratio of the antenna
- To calculate the front-to-back ratio of the antenna

Which of the following factors may affect the feed point impedance of an antenna?

- Transmission-line length
- Antenna height, conductor length/diameter ratio and location of nearby conductive objects
- The settings of an antenna tuner at the transmitter
- Sunspot activity and time of day

What is included in the total resistance of an antenna system?

- Radiation resistance plus space impedance
- Radiation resistance plus transmission resistance
- Transmission-line resistance plus radiation resistance
- Radiation resistance plus ohmic resistance

How does the beamwidth of an antenna vary as the gain is increased?

What is meant by antenna gain?

- The ratio of the radiated signal strength of an antenna in the direction of maximum radiation to that of a reference antenna
- The ratio of the signal in the forward direction to that in the opposite direction
- The ratio of the amount of power radiated by an antenna compared to the transmitter output power
- The final amplifier gain minus the transmission line losses

What is meant by antenna bandwidth?

- Antenna length divided by the number of elements
- The frequency range over which an antenna satisfies a performance requirement
- The angle between the half-power radiation points
- The angle formed between two imaginary lines drawn through the element ends

How is antenna efficiency calculated?

- (radiation resistance / transmission resistance) x 100 percent
- (radiation resistance / total resistance) x 100 percent
- (total resistance / radiation resistance) x 100 percent
- (effective radiated power / transmitter output) x 100 percent

Which of the following choices is a way to improve the efficiency of a ground-mounted quarter-wave vertical antenna?

- Install a good radial system
- Isolate the coax shield from ground
- Shorten the radiating element
- Reduce the diameter of the radiating element

Which of the following factors determines ground losses for a ground-mounted vertical antenna operating in the 3 MHz to 30 MHz range?

How much gain does an antenna have compared to a 1/2-wavelength dipole when it has 6 dB gain over an isotropic antenna?

How much gain does an antenna have compared to a 1/2-wavelength dipole when it has 12 dB gain over an isotropic antenna?

What is meant by the radiation resistance of an antenna?

- The combined losses of the antenna elements and feed line
- The specific impedance of the antenna
- The value of a resistance that would dissipate the same amount of power as that radiated from an antenna
- The resistance in the atmosphere that an antenna must overcome to be able to radiate a signal

What is the effective radiated power relative to a dipole of a repeater station with 150 watts transmitter power output, 2 dB feed line loss, 2.2 dB duplexer loss, and 7 dBd antenna gain?

What is the effective radiated power relative to a dipole of a repeater station with 200 watts transmitter power output, 4 dB feed line loss, 3.2 dB duplexer loss, 0.8 dB circulator loss, and 10 dBd antenna gain?

What is the effective radiated power of a repeater station with 200 watts transmitter power output, 2 dB feed line loss, 2.8 dB duplexer loss, 1.2 dB circulator loss, and 7 dBi antenna gain?

What term describes station output, taking into account all gains and losses?