E9H: Effective radiated power; system gains and losses; radio direction finding antennas
E9H01:
What is the effective radiated power 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?
286 watts
1977 watts
78.7 watts
420 watts
E9H02:
What is the effective radiated power 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?
317 watts
2000 watts
126 watts
300 watts
E9H03:
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-dBd antenna gain?
252 watts
159 watts
632 watts
63.2 watts
E9H04:
What term describes station output (including the transmitter, antenna and everything in between), when considering transmitter power and system gains and losses?
Effective radiated power
Power factor
Half-power bandwidth
Apparent power
E9H05:
What is the main drawback of a wire-loop antenna for direction finding?
It has a bidirectional pattern
It is non-rotatable
It receives equally well in all directions
It is practical for use only on VHF bands
E9H06:
What is the triangulation method of direction finding?
Antenna headings from several different receiving stations are used to locate the signal source
The geometric angle of sky waves from the source are used to determine its position
A fixed receiving station plots three headings from the signal source on a map
A fixed receiving station uses three different antennas to plot the location of the signal source
E9H07:
Why is an RF attenuator desirable in a receiver used for direction finding?
It prevents receiver overload from extremely strong signals
It narrows the bandwidth of the received signal
It eliminates the effects of isotropic radiation
It reduces loss of received signals caused by antenna pattern nulls
E9H08:
What is the function of a sense antenna?
It modifies the pattern of a DF antenna array to provide a null in one direction
It increases the sensitivity of a DF antenna array
It allows DF antennas to receive signals at different vertical angles
It provides diversity reception that cancels multipath signals
E9H09:
What is a receiving loop antenna?
One or more turns of wire wound in the shape of a large open coil
A large circularly-polarized antenna
A small coil of wire tightly wound around a toroidal ferrite core
Any antenna coupled to a feed line through an inductive loop of wire
E9H10:
How can the output voltage of a receiving loop antenna be increased?
By increasing either the number of wire turns in the loop or the area of the loop structure
By reducing the permeability of the loop shield
By increasing the number of wire turns in the loop and reducing the area of the loop structure
By reducing either the number of wire turns in the loop or the area of the loop structure
E9H11:
Why is an antenna with a cardioid pattern desirable for a direction-finding system?
The response characteristics of the cardioid pattern can assist in determining the direction of the desired station
The broad-side responses of the cardioid pattern can be aimed at the desired station
The extra side lobes in the cardioid pattern can pinpoint the direction of the desired station
The high-radiation angle of the cardioid pattern is useful for short-distance direction finding
E9H12:
What is an advantage of using a shielded loop antenna for direction finding?
It is electro-statically balanced against ground, giving better nulls
It automatically cancels ignition noise pickup in mobile installations
It eliminates tracking errors caused by strong out-of-band signals
It allows stations to communicate without giving away their position
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