What is VSWR?

What is VSWR in case of Mobile Antennas?

vswr meter

VSWR stands Voltage Standing wave Ratio.
VSWR is a number which describes how well an antenna is matched to the system.
VSWR describes the power reflected back by the antenna.
VSWR is less means, the antenna works well.
If the antenna and the feeding line does not match, then some of the electrical energy cannot be transferred from the feedline to the antenna.and it is  reflected back towards the transmitter. The interaction of these reflected waves with forward waves which causes standing wave patterns.

What are the implications of higer VSWR?
Radio Frequency  energy losses increase
Distortion on transmitter due to reflected power from load
Damage to the transmitter can occur


Then how to match the antenna and feeder?
It can be done by  antenna tuner. The tuner can be installed between the transmitter and the feed line, or between the feed line and the antenna. Both installation methods will allow the transmitter to operate at a low SWR, however if the tuner is installed at the transmitter, the feed line between the tuner and the antenna will still operate with a high SWR, causing additional RF energy to be lost through the feedline.

What is a good value of VSWR for my antenna?
VSWR=1  means Reflected Power is 0
VSWR=1.5 means Reflected Power is 4%
VSWR=3 means Reflected Power is 25%
VSWR=10 means Reflected Power is 70%
Generally speaking, if VSWR is less than 2, then the system is OK.


How to pronounce VSWR?

I pronounce this as V-S-W-R. But some people pronounce this as "viswar"


What is the definition for SWR?
The technical definition of Standing Wave Ratio is"It is   the ratio of the amplitude of a partial standing wave at an antinode (maximum) to the amplitude at an adjacent node (minimum), in an electrical transmission line.

What is mechanical tilt and Electrical tilting of Antenna?

Electrical tilting:

electrical tilting  is done by rotating the above white knob