Certification of Cable and Antenna Systems
Certification of Cable and Antenna Systems
To calculate VSWR for this scenario, simply take the ratio of the largest
Voltage Standing Wave Radio (VSWR)
standing wave to the smallest standing wave. In this case: VSWR= Vstanding1 / Vstanding2 = 1.2/0.8 = 1.5 Because VSWR and return loss are two ways to measure the same property,
Just like return loss, the VSWR test also indicates how well the cable and
you can use the following equations to convert between the two:
antenna system is matched. VSWR is also referred to as Standing Wave Ratio (SWR). It is also a measure of how efficiently RF power is transmitted from the power source, through the transmission line, and into the load. As its name implies, VSWR is calculated by taking the ratio of the largest to the smallest amplitude values of the standing wave created by the combination
VSWR =
1+10 1-10
-RL 20 -RL 20
RL = -20log10
VSWR-1 VSWR+1
of the incident and reflected waveforms. Values of VSWR range from one for a perfect impedance match to infinity for an open or short circuit. This scenario, in which both the incident and reflected waves are in phase (the standing wave has an amplitude that is the vector sum of the incident and reflected waves), shows the largest possible magnitude of the standing wave. Conversely, the smallest possible standing wave must then occur when the incident and reflected waves are 180 degrees out of phase.
Figure 21: Standing wave scenarios
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Optimized Commissioning of Fiber-to-the-Antenna Cell Sites
Figure 22: A sample VSWR measurement made with a CellAdvisor
Optimized Commissioning of Fiber-to-the-Antenna Cell Sites
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