Wireless Chapter 5
B. Antenna diversity 802.11a access points can use antenna diversity. Gain and polarization are considered RF concepts.
802.11a access points support which antenna technology to help reduce the effects of multipath? A. Adjustable gain B. Antenna diversity C. Adjustable polarization D. Antenna multiplexing
RF line of sight (LoS)
A clear path for the RF energy to travel between two points is what?
C) 8'
A grounding rod should be driven at least how far into the ground? A) 6' B) 7' C) 8' D) 9' E) 5' - 25'
A. Semidirectional A patch antenna provides semidirectional coverage. The amount of coverage depends on the design and gain of the antenna. Parabolic dishes are highly directional.
A patch antenna is an example of which type of antenna? A. Semidirectional B. Omnidirectional C. Highly directional D. Dipole-directional
D. 60 It is recommended that at least 60 percent of the Fresnel zone be free of obstruction in order to have acceptable RF line of sight. Up to 40 percent of the zone can be blocked by obstructions without affecting the signal.
A point-to-point wireless link requires what percent of the Fresnel zone to be clear in order to be considered to have an acceptable RF line of sight? A. 0 B. 20 C. 40 D. 60
antenna
A(n) ___________ takes the modulated RF energy from the transmission system, transforms it into radio waves, and propagates it through the free air.
A. One 802.11g access points require only one antenna to function. Systems that support antenna diversity will require two antennas to correctly operate.
An IEEE 802.11g access point requires a minimum of how many antennas to move data? A. One B. Two C. Four D. Six
B. Horizontal The horizontal RF radiation pattern of an antenna is displayed using an azimuth chart. The vertical radiation pattern is displayed using an elevation chart.
An azimuth chart shows which RF radiation pattern? A. Vertical B. Horizontal C. Positive D. Negative
E) 360
An omnidirectional antenna has a horizontal beamwidth of how many degrees? A) 45 B) 90 C) 120 D) 180 E) 360
horizontally vertically degrees
Antenna beamwidth is measured both __________ and __________ in ___________.
B) dBi (decibels isotropic)
Antenna gain is measure in what? A) dBm B) dBi C) Watts D) mW E) dB
B. Passive Antennas provide an increase in RF coverage by means of passive gain. Passive gain occurs when isotropic RF energy is focused into a specific radiation pattern. Active gain requires the use of an external power source.
Antennas provide an increase in RF coverage by using ____________ gain. A. Active B. Passive C. Positive D. Maximum
gain
Directed changing of the RF beamwidths is measured in ________.
C) Omnidirectional/half wave dipole antennas
Most access points use: A) Semidirectional antennas B) Multidirectional antennas C) Omnidirectional/half wave dipole antennas D) Highly directional antennas E) Half-directional/Semi dipole antennas
D. 360 Omnidirectional antennas have a horizontal beamwidth of 360°. The vertical beamwidth will vary depending on the design and the gain of the antenna.
Omnidirectional antennas have a horizontal beamwidth ____________ of degrees. A. 90 B. 180 C. 270 D. 360
A. Active Active gain requires an external power source to provide an increase in signal strength. An amplifier is an example of a device that uses active gain. Antennas provide an increase in strength by using passive gain.
Powered amplifiers provide an increase in signal strength by using ____________ gain. A. Active B. Passive C. Positive D. Maximum
A. Point-to-point C. Point-to-multipoint Point-to-point and point-to-multipoint both require RF line of sight to be able to effectively communicate. Scattering, reflection, and refraction are all behaviors of RF.
RF line of sight is required for which type of IEEE 802.11 WLAN installation? (Choose two.) A. Point-to-point B. Scattered C. Point-to-multipoint D. Reflected E. Refracted
B) ohms
Resistance is measure in: A) voltage B) ohms C) capacitance D) dBi E) inductance F) watts
omnidirectional semidirectional
Sector antennas can be used to create ______________ radiation patterns using ____________ antennas.
amplitude
The amount of power of a sine wave is _______?
A) Omnidirectional/half wave dipole antennas C) Semidirectional antennas D) Highly directional antennas
The book lists three common types of antennas used in WLANs, identify them: A) Omnidirectional/half wave dipole antennas B) Multidirectional antennas C) Semidirectional antennas D) Highly directional antennas E) Half-directional/Semi dipole antennas
B. 7 The curvature of the earth or earth bulge will have an impact on a WLAN signal after seven miles. If the signal needs to travel farther than seven miles, the antenna will have to be installed in a higher location.
The curvature of the earth will have an impact on the WLAN signal after how many miles? A. 2 B. 7 C. 10 D. 25
A. Omnidirectional The image is an example of an omnidirectional antenna. This type of antenna provides a horizontal radiation pattern of 360°.
The following graphic shows which type of antenna? A. Omnidirectional B. Yagi C. Patch/panel D. Parabolic dish
D. Semidirectional The image shows a patch antenna. This is an example of a semidirectional antenna.
The following image shows which type of antenna? A. Highly directional B. Dipole-directional C. Omnidirectional D. Semidirectional
torus
The shape of the radiation pattern for an omnidirectional antenna looks like a doughnut and is known as a _______________.
Beamwidth
These characteristics, horizontal and vertical angles, describe what antenna concept?
reflection refraction scattering diffraction
This chapter reiterates four behaviors of RF, name them.
Radio frequency lobes
This describes the shape of the radiation patterns.
passive gain
This is a change in coverage without the use of an external power source.
pigtail
This is a name of a short length of cable.
visual line of sight (LoS)
This is defined as the capability of two points to have an unobstructed view of one another.
FALSE, it's radome you big idiot. I'm just kidding, you're amazing.
True or false, A rabome cover will protect an antenna from outdoor elements an certain weather conditions.
True
True or false, As the signal propagates away from the antenna, the RF coverage naturally diffuses.
False, a single radio that transmits and receive radio signals is known as single-input, single-output SISO technology
True or false, IEEE 802.11a/b/g devices use a single radio to transmit and receive radio signals, which is known as MIMO
True, I added 'entirely' in that sentence because I wanted more words that started with 'e'
True or false, Isotropic energy is defined as energy emitted entirely equally in all directions.
True
True or false, Omnidirectional antennas are one of the most common types of antennas for indoor WLAN deployments.
False, it describes the orientation.
True or false, Polarization describes horizontal and parallel wave strength.
False, it's called the Fresnal zone.
True or false, The area of RF coverage surrounding the visual line of sight is called the Freznal zone.
False, elevation is the vertical pattern and azimuth is a weird word.
True or false, The azimuth refers to the horizontal RF pattern while the elevation refers to the parallel RF pattern.
True
True or false, Wind loading is the result of wind blowing at high speeds and causing the antenna to move.
False, loss only not gain
True or false, using connectors can result in insertion loss or gain.
outdoor
Typically, are highly directional antennas used for either outdoor or indoor use?
D) parabolic note F) grid -> parabolic dishes are either solid or grid so F) is sort of correct
Which antennas are both highly directional and used for long-range point-to-point bridge connections? Choose all that apply: A) panel B) patch C) rubber duck D) parabolic E) Yagi F) grid G) sector
C. Cable D. Connector Cables and connectors can both result in a loss of signal strength. Antennas and amplifiers will add gain or increase signal strength. A transmitter outputs an absolute amount of power.
Which can cause a loss of signal strength? (Choose two.) A. Antenna B. Amplifier C. Cable D. Connector E. Transmitter
Type of cable Length of cable Cost of cable Impedance rating
Which factors should be considered when choosing RF cables and connectors?
E) Yagi
Which specific antennas are designed to be used indoors in long hallways and corridors, or outdoors for short-range bridging (typically less than two miles)? Choose all that apply. A) rubber duck B) patch C) panel D) parabolic E) Yagi F) grid G) sector
C. Wind Of the answers listed, wind would have the biggest impact on a WLAN system. Rain, snow, and hail do not affect wireless transmission unless the weather is severe. In this case, the collection of the elements may have an impact on the WLAN signal transmitted or received.
Which weather element would commonly have an effect on a WLAN system? A. Rain B. Snow C. Wind D. Hail
Proprietary connectors prevent an install or integrator from unintentionally using an antenna that might exceed the maximum amount of power allowed for the transmission system.
Why would some regulatory domains require the use of proprietary connectors?
C. 50 WLAN cables and devices are rated at 50 ohms impedance. Cable and satellite television is rated at 75 ohms.
Wireless network cables and devices have impedance (AC resistance) of ____________ ohms. A. 10 B. 25 C. 50 D. 75
decrease increase
With an omnidirectional antenna, higher gain causes the vertical coverage to ______________ and the horizontal coverage to ______________.
Active gain
________ _______ is accomplished by providing an external power source to an installed device.
Antenna charts
________ _________ illustrate Azimuth and elevation.
Antenna diversity multipath
____________ ________________ is a technology used in IEEE 802.11a/b/g WLANs; a station (access point or client device) will utilize two antennas combined with one radio to decrease the effects of _______________.
Impedance
_________________ is the measurement of alternating current (AC) resistance.
Multipath
__________________ is the result of several wavefronts of the same transmission signal received out of phase at slightly different times.
transmitted received
Higher levels of voltage standing wave ratio can impact a WLANs ________________ or ______________ signal.
C. Long-range
Highly directional antennas are typically used for ____________ connectivity. A. Short-range B. Omnidirectional C. Long-range D. Dipole
C. Long-range Highly directional antennas are typically used for long-range point-to-point connectivity, such as bridge links. Omnidirectional antennas are used as part of an access point system or to provide point-to-multipoint links.
Highly directional antennas are typically used for ____________ connectivity. A. Short-range B. Omnidirectional C. Long-range D. Dipole
A. Parallel Horizontal beamwidth is parallel to the earth's surface. This is based on how the E-field propagates away from the antenna element. Vertical beamwidth is perpendicular to the earth's surface.
Horizontal beamwidth is ____________ to the earth's surface. A. Parallel B. Perpendicular C. Positive D. Negative
B. Two An IEEE 802.11a or IEEE 802.11b/g access point will require two antennas for diversity. Although there are two antennas, a single input/single output access point will have only one radio. The access point provides additional intelligence to determine which antenna to use. Other WLAN technologies, such as IEEE 802.11ac MIMO, may use multiple antennas.
IEEE 802.11a/b/g access points require ____________ antennas on each radio for diversity functionality. A. One B. Two C. Three D. Six
single-input single-output (SISO)
IEEE 802.11a/b/g antennas use one radio to transmit and receive radio signals, what is this technology called?
B) patch C) panel E) sector G) Yagi
Identify the various types of semidirectional antennas available from this list, choose all that apply: A) rubber duck B) patch C) panel D) parabolic E) sector F) grid G) Yagi
50%
In beamwidth, the RF power decreases by what percentage?
B) 1
In diversity systems, two antennas are spaced at least how many wavelengths apart? A) 3 B) 1 C) 2 D) 4 E) 25 F) 22
in-series
Lightning arrestors are installed ________ after the antenna and prior to the receiver/transmitter.
It defines the projecting part of the signal, in it's most intended usage, the "main signal"
Lobe defines which part of the signal?
impedance mismatches
VSWR is the result of ______________ _____________.
D) 50 ohms
WLANs use cable rated at: A) 50 dBi B) 50 w C) 50 mW D) 50 ohms
B. Lightning arrestor A lightning arrestor is used to protect a WLAN system from an indirect lightning strike. A lightning arrestor will direct transient or induced electrical current to earth ground as a result of a lightning strike.
What device is used to shunt transient current to ground in the event of an indirect lightning strike? A. Lightning striker B. Lightning arrestor C. Lightning prevention D. Lightning breaker
voltage standing wave ratio
What does VSWR stand for?
received signal strength indicator
What is RSSI?
gain
What is it called when an antenna provides a change in a coverage pattern that is a result of the antenna focusing the area of RF propagation.
Polarization describes how a wave is emitted from an antenna and the orientation of the electrical component or electric field of the waveform.
What is polarization?
beamwidth
What is the angle of measurement of the main RF lobe measured at the half-power point or power?
The azimuth of sector antennas is between 90 and 180 degrees.
What is the azimuth of sector antennas?
3 to 15 degrees
What is the beamwidth range of highly directional antennas?
5 and 25 ohms
What is the measure of resistance that a grounding rod should measure?
rubber duck antenna 2 to 3 dBi
What is the most common type of omnidirectional antenna called and what is the typical gain?
Antenna diversity
What technology helps to reduce the effects of multipath?
From center to the outside ring the signal goes from strongest to weakest in dB.
When reading an Azimuth and Elevation Chart, how does the chart read, in terms of signal strength from center to the outer ring and in what unit is the strength measured?
A) 802.11g C) 802.11b D) 802.11a
Which IEEE 802.11 standards utilize antenna diversity? Choose all that apply. A) 802.11g B) 802.11n C) 802.11b D) 802.11a E) 802.11ac
Omnidirectional
Which antenna type is most common on most access points of either SOHO or enterprise grade?
sector
Which antennas are a type of semidirectional antenna that can be configured in an array to provide omnidirectional coverage?
