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2-58. Bulk-effect semiconductors have what
primary advantage over normal pn-
junction semiconductors?
1. Smaller size
2. Lower frequency
3. Simpler construction
4. Greater power output
2-59. Gallium-arsenide semiconductors begin
to exhibit which of the following
electrical characteristics at the threshold
point?
1. Variable inductance
2. Positive resistance
3. Negative resistance
4. Variable capacitance
2-60. In an avalanche transit-time diode, what
causes the dc bias energy previously
absorbed by avalanche electrons to be
given up to the microwave field?
1. The electron velocity
2. The negative-resistance property
3. The electron transit time
4. The amount of dc bias energy
available
2-61. In a point-contact diode, passing a large
current from the catwhisker to the silicon
crystal produces what region?
1. A domain region
2. A small p region
3. A small n region
4. An avalanche region
2-62. A Schottky barrier diode has which of
the following advantages over a point-
contact diode?
1. Lower frequency range
2. Higher frequency range
3. Lower noise generation
4. Higher noise generation
2-63. The PIN diode begins acting as a variable
resistance at what minimum frequency?
1. 100 megahertz
2. 200 megahertz
3. 300 megahertz
4. 400 megahertz
2-64. Power ratio is a term used to express
what property of an antenna?
1. Efficiency
2. Reciprocity
3. Sensitivity
4. Power output
2-65. A standing-wave ratio (swr) describes
which of the following quantities?
1. Transmission-to-reception efficiency
value
2. The amount of output power
3. The amount of mismatch between a
transmission line and its load
4. The amount of characteristic
impedance
2-66. Directivity refers to which of the
following properties of a radiated beam?
1. Power gain
2. Standing-wave ratio
3. Narrowness of the beam
4. Polarization of the beam
2-67. Surface angular measurements for
antenna directivity in radar and
communications systems are made in
relationship to which of the following
references?
1. Vertical plane only
2. Horizontal plane only
3. Horizontal plane and true north
4. Vertical plane and true north
