Deck 4: How Antennas Work

Question 1

What does antenna polarization determine about the performance of the antenna?

A) radiation pattern
B) horizontal or vertical orientation
C) measurement of signals is positive or negative voltage
D) direction of the signal

Answer 1

B

Question 2

Cables and connectors offer resistance to the flow of electricity, increasing the power of a signal.

Answer 2

False

Question 3

A monopole antenna is a type of two-dimensional antenna.

Answer 3

False

Question 4

If a signal is represented as 15 mW + 10 db, what is the resulting signal strength in mW?

A) 30 mW
B) 25 mW
C) 75 mW
D) 150 mW

Question 5

Which type of antenna is two-dimensional, is common in telephone networks, and is used to transmit high-power microwave signals between towers?

A) patch
B) satellite dish
C) horn
D) dipole

Question 6

Which of the following is true about omnidirectional antennas?

A) they work best in point-to-point links
B) they cannot be used in 802.11 applications
C) longer ones usually have higher gain
D) they emit a signal in three dimensions

Question 7

Which of the following is true about antennas?

A) the size is proportional to the wavelength
B) lower frequency signals require larger antennas
C) most are active devices
D) omnidirectional types provide the best directional gain

Question 8

Which of the following is likely to result in a wireless signal gain?

A) cables
B) amplifier
C) connectors
D) atmosphere

Question 9

What type of antenna is divided into a matrix of radiating elements and are used in modern radar systems?

A) switched beam
B) horn
C) patch
D) phased array

Question 10

A cellular phone antenna that is 13 inches long would be considered which of the following?

A) eighth-wave
B) quarter-wave
C) half-wave
D) full-wave

Question 11

What unit of measurement is a ratio between two signal levels?

A) volt
B) watt
C) decibel
D) ohm

Question 12

Decibels are an absolute measurement of signal strength, making it simpler to calculate gain or loss.

Question 13

The size of an antenna is directly proportional to the wavelength of the signal it is designed to transmit and receive.

Question 14

Point-to-point wireless links are best served by using omnidirectional antennas.

Question 15

What type of antenna is a straight piece of wire with no reflecting ground element?

A) monopole
B) dipole
C) horn
D) dish

Question 16

Which of the following refers to the gain an antenna has over a dipole antenna at the same frequency?

A) dBm
B) dBd
C) dBi
D) dBg

Question 17

Which value indicates the signal being measured is twice the power?

A) +3 dB
B) -5 dB
C) +5 mW
D) -3 mW

Question 18

When a coaxial cable connects the antenna to the transmitter, what property of the cable must match that of the antenna?

A) impedance
B) thickness
C) length
D) inductance

Question 19

Which type of directional antenna is used for outdoor applications up to 16 miles?

A) cellular
B) patch
C) parabolic dish
D) yagi

Question 20

If an antenna is much longer than the wavelength, what is the typical result?

A) inefficient delivery of RF energy
B) signals that are an incorrect wavelength
C) wrong signal frequency
D) no signal is transmitted

Question 21

What is the signal strength necessary to meet a receiver's minimum requirements?

A) transmission path
B) Fresnel zone
C) minimum wavelength
D) link budget

Question 22

Which of the following is the elliptical region within which signals travel between two antennas in a point-to-point link?

A) troposphere radius
B) propagation limit
C) Fresnel zone
D) wave pattern

Question 23

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
the relative measurement of the gain of an antenna when compared to a theoretical isotropic radiator

Question 24

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
a semi-directional antenna that emits a wide horizontal beam and an even
wider vertical beam

Question 25

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
the signal loss that occurs as a result of the tendency of RF waves to spread

Question 26

______________ is the effect of an amplifier boosting the power of a signal.

Question 27

A radio signal's power does not change in a linear fashion, but instead changes ______________.

Question 28

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
a relative way to indicate an absolute power level in the linear watt scale

Question 29

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
a metal disc or two straight wires assembled at 90 degrees, used to provide
a reflection point for monopole antennas

Question 30

What type of wave propagation do RF signals transmitted at 50 MHz have?

A) ground waves
B) sky waves
C) line-of-sight waves
D) atmospheric waves

Question 31

_____________ is a relative measurement used to represent gain or loss in a signal.

Question 32

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
a theoretically perfect sphere that radiates power equally in all directions

Question 33

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
a graphic that shows how a signal radiates out of an antenna

Question 34

When considering antenna size, lower frequencies require ___________ antennas.

Question 35

A _________________ analyzer is a tool that displays the signal amplitude and frequency of a radio transmission.

Question 36

What is the maximum percent of the Fresnel zone that can be blocked by obstructions in a point-to-point link?

A) 20%
B) 60%
C) 40%
D) 10%

Question 37

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
can only radiate a signal with the same amount of energy that appears at the antenna connector

Question 38

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
a new type of antenna that uses a signal processor and an array of narrow beam elements

Question 39

MATCHING
a. antenna pattern
b. dB isotropic
c. dBm
d. dipole
e. free space loss
f. ground-plane
g. isotropic radiator
h. passive antenna
i. patch antenna
j. smart antenna
an antenna that has a fixed amount of gain over that of an isotropic radiator

Question 40

Which type of antenna should usually be used at the central location in a point-to-multipoint wireless link?

A) unidirectional
B) omnidirectional
C) directional
D) semi-directional

Question 41

Describe the "tens and threes of RF mathematics".

Question 42

List three of the four aspects of RF signal transmission you need to know.

Question 43

How does the size of an antenna affect its ability to transmit and receive?

Question 44

What does antenna polarization tell you about the antenna wave? How is it important for signal reception?

Question 45

What is an isotropic radiator?

Question 46

What is free space loss? Describe how it occurs.

Question 47

Give two examples of two-dimensional antennas. Describe them.

Question 48

What are two types of directional antenna? Describe them.

Question 49

What does an antenna pattern show about the RF wave?

Question 50

Describe directional gain and how it can be accomplished with a passive antenna.