Capítulo 1: Fundamentación Teórica
1.7. Lenguaje de programación
1. ' parametric amplifier must be cooled
a. because parametric amplification generates a lot of heat b. to increase bandwidth
c. because it cannot operate at room temperature
. t$ i!'#$&e the n$i"e 'e#f$#!ance 2. ' ruby maser amplifier must be cooled
a. because maser amplification generates a lot of heat b. to increase bandwidth
c. becau"e it cann$t $'e#ate at #$$! te!'e#atu#e d. to improve the noise performance
3. ' disadvantage of microstrip compared with stripline is that microstrip a. does not readily lend itself to printed circuit techni#ues
b. i" !$#e liel( t$ #aiate c. is bulkier
d. is more e&pensive and comple& to manufacture
. %he transmission system using two ground plane is a. microstrip
b. elliptical waveguide c. parallel"wire line
. "t#i'line
!. Indicate the false statement. 'n advantage of stripline over wveguide is its
a. smaller bulk b. greater bandwidth
c. hi)he# '$%e#/hanlin) ca'abilit(
d. greater compatibility with solid"state devices
$. Indicate the false statement. 'n advantage of stripline over microstrip is its
a. ea"ie# inte)#ati$n %ith "e!ic$nuct$# e&ice"
b. lower tendency to radiate
c. higher isolation between adBacent circuits d. higher L
+. 5urface acoustics waves propagate in a. gallium arsenide
b. indium phosphide c. stripline
. 0ua#t2 c#("tal
-. 5' devices may be used as
a. t#an"!i""i$n !eia lie "t#i'line b. filters
c. 0)F amplifiers
d. scillators at millimeter fre#uencies
. Indicate the false statement. F%s are preferred to bipolar transistors at the highest fre#uencies because they
a. are less noisy
b. len the!"el&e" !$#e ea"il( t$ inte)#ati$n c. are capable of higher effeciencies
d. can provide higher gains
1(. For best low"level noise performance in the "band, an amplifier should use
a. a bipolar transistor b. a 7unn diode
c. a "te'/#ec$&e#( i$e d. an IMC'%% diode
11. %he biggest advantage of the %8'C'%% diode over the IMC'%% diode is its
a. lower noise
b. hi)he# efficienc(
c. ability to operator at higher fre#uencies d. lesser sensitivity to harmonics
12. Indicate which of the following diodes will produce the highest pulsed power output
a. 9arator b. 7unn
c. 5chottky barrier
. RIMPATT
13. Indicate which of the following diodes does not use negative resistnace in its operation
a. 1ac%a#
b. 7unn c. IMC'%%
d. %unnel
1. ne of the following is not used as a microwave mi&er or detector
a. 6rystal diode
b. 5chottky"barrier diode c. <ackward diode
. PIN i$e
1!. ne of the following microwave diodes is suitable for very low"power oscillators only
a. Tunnel b. avalanche
c. 7unn d. IMC'%%
1$. %he transferred"electron bulk effect occurs in a. germanium
b. )alliu! a#"enie c. silicon
d. metal semiconductor Bunctions
1+. %he gain"bandwidth fre#uency of a microwave transistor, f !" is the fre#uency at which the
a. alpha of the transistor falls by 3 d<
b. beta of the transistor falls by 3 d<
c. power gain of the transistor falls to unity
. beta $f the t#an"i"t$# fall" t$ unit(
1-. For a microwave transistor to operate at the highest fre#uencies, the
=indicate the false answer>
a. collector voltage must be large b. collector current must be high
c. base should be thin
. e!itte# a#ea !u"t be la#)e
1. ' varactor diode may be useful at microwave fre#uencies =indicate the false answer>
a. for electronic tuning b. for fre#uency multiplication
c. a" an $"cillat$#
d. as a parametric amplifier
2(. If high"order fre#uency multiplication is re#uired from a diode multiplier,
a. the resistive cutoff fre#uency must be high b. a small value of the base resistance is re#uired
c. a "te'/#ec$&e#( i$e !u"t be u"e
d. a large range of capacitance variation is needed
21. ' parametric amplifier has an input and output fre#uency of 2.2! 7)*, and is pumped at .! 7)*. It is
a. traveling"wave amplifier b. e)ene#ati&e a!'lifie#
c. lower"sideband up"converter d. upper"sideband up"converter
22. ' nondegenerate parametric amplifier has an input fre#uency f and ai pump fre#uency f . %hen idler fre#uency is p
a. f i b. 2 f i
c. f N f i p
. f / f
p i
23. %raveling"wave parametric amplifiers are used to a. provide a greater gain
b. reduce the number of varactor diodes re#uired c. avoid the need for cooling
. '#$&ie )#eate# ban%ith
2. ' parametric amplifier sometimes uses a circulator to a. '#e&ent n$i"e feebac
b. allow the antenna to be used simultaneously for transmission and reception
c. separate the signal and idler fre#uencies d. permit more efficient pumping
2!. %he nondegenerate one"port parametric amplifier should have a high ratio of pump to signal fre#uency because this
a. permits satisfactory high"fre#uency operation b. (iel" a l$% n$i"e fi)u#e
c. reduce the pump power re#uired d. permits satisfactory
2$. %he tunnel diode
a. has a tiny hole through its center to facilitate tunneling
b. is a point"contact diode with a very high reverse resi stance c. u"e" a hi)h $'in) le&el t$ '#$&ie a na##$% 5uncti$n
d. works by #uantum tunneling e&hibited by gallium arsenide only 2+. ' tunnel diode is loosely coupled to its cavity in order to
a. inc#ea"e the f#e0uenc( "tabilit(
b. increase the available negative resistance c. facilitate tuning
d. allow operation at the highest fre#uencies 2-. %he negative resistance in a tunnel diode
a. is ma&imum at the peak point of the characteristic b. i" a&ailable bet%een the 'ea an &alle( '$int"
c. is ma&imum at the valley point
d. may be improved by the use of reverse bias
2. %he biggest advantage of gallium antimonide over germanium for tunnel"
diode use it that former has a a. lower noise
b. higher ion mobility c. la#)e# &$lta)e "%in) d. simpler fabrication process
3(. 4egative resistance is obtained with a 7unn diode because of a. elect#$n t#an"fe# t$ a le"" !$bile ene#)( le&el
b. avalanche breakdown with the high voltage gradient c. tunneling across the Bunction
d. electron domains forming at the Bunction
31. For 7unn diodes, gallium arsenide is preferred to silicon because the former
a. ha" a "uitable e!'t( ene#)( ban= %hich "ilic$n $e" n$t ha&e b. has a higher ion mobility
c. has a lower noise at the highest fre#uencies d. is capable of handling higher power densities 32. %he biggest disadvantage of the IMC'%% diode is its
a. lower efficiency than that of the other microwave diodes b. hi)h n$i"e
c. inability to provide pulsed operation d. low power"handling ability
33. %he magnetic field is used with a ruby maser to a. provide sharp focusing for the electron beam b. increase the population inversion
c. allow room"temperature operation
. '#$&ie f#e0uenc( a5u"t!ent"
3. %he ruby maser has been preferred to the ammonia maser for microwave amplification, because the former has
a. a !uch )#eate# ban%ith b. a better fre#uency stability
c. a lower noise figure d. no need for a circulator
3!. Carametric amplifiers and masers are similar to each other in that both =indicate false statement>
a. must have pumping
b. are e&tremely low"noise amplifiers c. !u"t be c$$le $%n t$ a fe% el&in"
d. generally re#uired cicultators, since they are one"port devices 3$. ' maser 8F amplifier is not really suitable for
a. radioastronomy
b. satellite communications c. #aa#
d. troposcatter receiver
3+. %he ruby laser differs from the ruby maser in that the former a. does not re#uire pumping
b. needs no resonator c. i" an $"cillat$#
d. produces much lower powers
3-. %he output from a laser is monochromatic; this means that it is a. infrared
b. polari*ed c. narrow"beam
. "in)le/f#e0uenc(
3. For a given average power, the pea# output power of a ruby laser may be increased by
a. using cooling
b. u"in) Q"'$ilin)
c. increasing the magnetic field
d. dispensing with the Fabry"Cerot resonator
(. 6ommunications lasers are used with optical fiber, rather than in open links, to
a. ensure that the beam does not spr ead b. '#e&ent at!$"'he#ic inte#fe#ence
c. prevent interference by other laser
d. ensure that people are not blinded by them
1. Indicate the false statement. %he advantages of semiconductor lasers over :?s include
a. monochromatic output b. higher power output
c. l$%e# c$"t
d. ability to be pulsed at higher rates