1) CWNPCert: Wireless LAN Administration
Objective: Radio Frequency (RF) Technologies
SubObjective: RF Fundamentals
Single Answer Multiple Choice
Which option is the proper approach to preventing Voltage Standing Wave Ratio (VSWR)?
A. Assuring that all cables between the transmitter and the antenna do not exceed their maximum lengths
B. Maintaining a matching impendence on all cables and connectors between the transmitter and receiver
C. Using the highest quality cable allowed in the budget
D. Purchasing all connectors from the same manufacturer
Answer:
B. Maintaining a matching impendence on all cables and connectors between the transmitter and receiver
Tutorial:
VSWR is caused by a mismatch in the impedance or resistance (measured in Ohms) in either the cables or the connectors between the transmitter and receiver. The relationship between impedance in a cable and in a connector is referred to as a ratio. Thus a 1:1 ratio would be an exact match and a 1.5:1 ratio would represent one end having 50% more resistance than the other. A mismatch can cause loss of amplitude, or and extreme mismatch could damage the transmitter.
Assuring proper cable length and using high quality cabling is important for maintaining data quality, but has no effect on VSWR.
Purchasing all connectors from the same manufacturer will not prevent VSWR unless the connectors are rated at the same impedance.
Reference:
CWNA Official Study Guide Third Edition, pp. 39-41.
