Left Border Content - RF Cafe
Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Sub-Header - RF Cafe
Frequency-Agile Antennas for Wireless Communications
Answers to RF Cafe Quiz #57
All RF Cafe Quizzes make great fodder for
employment interviews for technicians or engineers - particularly those who are
fresh out of school or are relatively new to the work world. Come to think of it,
they would make equally excellent study material for the same persons who are going
to be interviewed for a job. Bonne chance, Viel Glück, がんばろう,
buena suerte, удачи, in bocca al lupo, 행운을 빕니다,
ádh mór, בהצלחה, lykke til, 祝你好運.
Well, you know what I mean: Good luck!
Click here for the complete list of
RF Cafe Quizzes.
Note: Some material based on books have
Return to RF Cafe
This quiz is based on the information presented in Frequency-Agile Antennas for Wireless
Communications, by Aldo Petosa.
Note: Some of these
books are available as prizes in the monthly
RF Cafe Giveaway.
1. To which class of antennas do frequency
agile antennas (FAAs) belong?
c) Active integrated antennas (AIAs)
context of this book, FAAs can be considered to belong to the larger class of antennas known
(see page 3)
2. How does antenna gain
differ from antenna directivity?
d) Gain accounts for losses as well as directivity
Directivity is a ratio of power relative to specific directions where losses up to the feed
point are already accounted for. An ideal antenna can be perfectly directional but still exhibit
(see page 9)
3. What are the two types
of tuning used in FAAs?
a) Discrete and continuous
Discrete tuning alters
the frequency to a fixed number of distinct values while continuous tuning can take on any tuning
(see page 15)
4. When did microstrip
antennas start coming into common use?
c) In the 1970s
technology was introduced in the 1960s, and microstrip antennas followed in the mid 1970s.
(see page 35)
5. For which microstrip patch antenna formats
does Frequency-Agile Antennas for Wireless Communications provide field equations?
a) Rectangular, dipole, circular, and annular (ring)
The basic design equations
are given for a few of the most popular microstrip patch antennas.
6. What type of tuning is typically available for
d) All the above
(see page 87)
How can the permittivity of ferroelectric substrates be altered?
b) By applying
an electric field
Ferroelectric substrates offer a behavior analogous to ferrites, where
the permittivity of the ferroelectric can be altered by the application of a static electric
(see Table 4.3 on page 103)
8. What methods
of mechanical tuning are practical for frequency agile antennas (FAAs)?
The types of actuators used include electrostatic, piezoelectric, magnetostatic,
hydraulic, and pneumatic. Information for each example includes tuning range, total spectrum,
bias requirements, and antenna performance.
(see page 149)
9. What is a major advantage of liquid crystals over ferroelectric substrates?
a) Lower bias voltage
The advantages of liquid crystals over ferroelectrics
include the much lower bias voltages required and the inherently low values of the dielectric
(see page 194)
10. What is the most
widely used component type for continuous tuning FFAs?
d) Varactor diodes
The majority of continuous tuning schemes use varactor diodes.
(see Table 7.1
on page 279)
Footer - RF Cafe
Right Border Content - RF Cafe