CWNP CWNA-109 Practice Test - Questions Answers, Page 3

List of questions
Question 21

What can an impedance mismatch in the RF cables and connectors cause?
VSWR stands for Voltage Standing Wave Ratio, which is a measure of how well the impedance of the RF cable and connectors matches the impedance of the transmitter and the antenna. Impedance is the opposition to the flow of alternating current in an RF circuit, and it depends on the frequency, resistance, capacitance, and inductance of the components. A perfect impedance match would have a VSWR of 1:1, meaning that all the power is transferred from the transmitter to the antenna, and none is reflected back. However, in reality, there is always some degree of mismatch, which causes some power to be reflected back to the transmitter, creating standing waves along the cable. This reduces the efficiency and performance of the wireless system, and can also damage the transmitter.Excessive VSWR can be caused by using poor quality or damaged cables and connectors, or by using components that have different impedance ratings123.Reference:CWNA-109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 90;CWNA-109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 86;CWNP website, CWNA Certification.
Question 22

What factor does not influence the distance at which an RF signal can be effectively received?
In wireless communication, several factors influence the effective reception of RF signals, including the receiving station's radio sensitivity, the transmitting station's output power, and free space path loss. However, the receiving station's output power does not influence the distance at which an RF signal can be effectively received. The key factors that impact signal reception distance are:
Receiving Station's Radio Sensitivity: This refers to the lowest signal strength at which the receiver can process a signal with an acceptable error rate. Higher sensitivity allows for better reception at greater distances.
Transmitting Station's Output Power: This is the power with which a transmitter sends out a signal. Higher output power can extend the range of transmission, making it easier for distant receivers to detect the signal.
Free Space Path Loss (FSPL): FSPL represents the attenuation of radio energy as it travels through free space. It increases with distance and frequency, reducing the signal strength as the distance from the transmitter increases.
The output power of the receiving station is related to how strong a signal it sends out, not how well it can receive or process incoming signals. Therefore, it does not affect the reception distance of incoming RF signals.
CWNA Certified Wireless Network Administrator Official Study Guide: Exam PW0-105, by David D. Coleman and David A. Westcott.
RF fundamentals and RF design considerations in wireless communication systems.
Question 23

A WLAN transmitter that emits a 50 mW signal is connected to a cable with 3 dB loss. If the cable is connected to an antenna with 9dBi gain, what is the EIRP at the antenna element?
To calculate the EIRP at the antenna element, we need to add the transmitter output power, subtract the cable loss, and add the antenna gain. All these values need to be converted to dBm first, if they are not already given in that unit. In this case, we have:
Transmitter output power = 50 mW = 10 log (50) dBm = 16.99 dBm Cable loss = 3 dB Antenna gain = 9 dBi
EIRP = Transmitter output power - Cable loss + Antenna gain EIRP = 16.99 - 3 + 9 EIRP = 22.99 dBm
Rounding up to the nearest integer, we get23 dBmas the EIRP at the antenna element12.Reference:CWNA-109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 92;CWNA-109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 88.
Question 24

In a long-distance RF link, what statement about Fade Margin is true?
Question 25

What wireless networking term describes the increase of RF energy in an intentional direction with the use of an antenna?
Question 26

Which directional antenna types are commonly used by indoor Wi-Fi devices in a MIMO multiple spatial stream implementation?
Question 27

What statement about the beamwidth of an RF antenna is true?
Question 28

Which one of the following is not a factor considered when calculating the Link Budget for an outdoor point-to- point WLAN bridge link?
Question 29

As an RF wave propagates through space, the wave front experiences natural expansion that reduces its signal strength in an are a. What describes the rate at which this expansion happens?
Question 30

You are implementing a VHT-capable AP. Which one of the following channels is available in the 802.11-2016 standard that was not available before the ratification of 802.11 ac?
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