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FAQ: Antennas >>>
It is not easy to give a limit for a good or bad antenna installation.
But here are some values which could be a guideline:
Fwd-Pwr Banten 1: 143
Fwd-Pwr Banten 2: 154
Fwd-Pwr Discone: 145
Fwd-Pwr no antenna: 34
Rev-Pwr Banten 1: 31
Rev-Pwr Banten 2: 15
Rev-Pwr Discone: 23
Rev-Pwr no antenna: 26
VSWR Banten 1: 4,6
VSWR Banten 2: 10,3
VSWR Discone: 6,3
VSWR no antenna: 1,3
Explanation of the table: When you start the Link2AIS program and look at the “Maintenance / Modem Data”, you can see the “forward power” (Fwd-Pwr) and the “reverse power” (Rev-Pwr).
1.) Please wait until the easyTRX has transmitted a message.
You can see that when the values are changing.
2.) Then divide the fwd-pwr by the rev-pwr values. You see that ratio in the VSWR-rows.
VSWF means “voltage standing wave ratio”
In the last row there is a value below 3 (VSWR no antenna: 1,3). That means it is bad. Of cause, because we had no antenna connected.
The other three columns show typical values, which are all perfect.
Conclusion: If the VSWR value is higher than 3, you have a good antenna installation and good cable connection.