# Frequency-Agile Antennas for Wireless CommunicationsRF Cafe Quiz #57

All RF Cafe quizzes would make perfect fodder in 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.

Note: Some material based on books have quoted passages.

This quiz is based on the information presented in Frequency-Agile Antennas for Wireless Communications, by Aldo Petosa.

Graciously provided by Artech House

1.  To which class of antennas do frequency agile antennas (FAAs) belong?

a)  Federal aviation antennas (FAAs)
b)  Passive integrated antennas (PIAs)
c)  Active integrated antennas (AIAs)
d)  Cross-Influenced Antennas (CIAs)

2.  How does antenna gain differ from antenna directivity?

a)  There is no difference
b)  Gain only applies to active antennas
c)  Gain can only be positive whereas directivity can be negative
d)  Gain accounts for losses as well as directivity

3.  What are the two types of tuning used in FAAs?

a)  Discrete and continuous
b)  High power and low power
c)  Manual and automatic
d)  Electronic and mechanical

4.  When did microstrip antennas start coming into common use?

a)  In the 1920s
b)  In the 1950s
c)  In the 1970s
d)  In the 1990s

5.  For which microstrip patch antenna formats does Frequency-Agile Antennas for Wireless Communications provide field equations?

a)  Rectangular, dipole, circular, and annular (ring)
b)  Spherical and tesseractical
c)  Cubical and spherical
d)  Tesseractical and cubical

6.  What type of tuning is typically available for antennas?

a)  Changing one or more physical dimensions
b)  Altering material properties
c)  Switching and/or tunable electronics
d)  All the above

7.  How can the permittivity of ferroelectric substrates be altered?

a)  By applying a mechanical stress
b)  By applying an electric field
c)  By harmonic inversion
d)  By optical manipulation

8.  What methods of mechanical tuning are practical for frequency agile antennas (FAAs)?

a)  Electrostatic and magnetostatic
b)  Piezoelectric
c)  Hydraulic and pneumatic
d)  All the above

9.  What is a major advantage of liquid crystals over ferroelectric substrates?

a)  Lower bias voltage
b)  Higher switching frequency
c)  Higher bandwidth
d)  Larger physical size

10.  What is the most widely used component type for continuous tuning FFAs?

a)  Schottky diodes
b)  Photodiodes
c)  MEMS
d)  Varactor diodes