How to measure an antenna's max RF capacity?

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Radio Liberdade
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How to measure an antenna's max RF capacity?

Post by Radio Liberdade »

Is there any way to measure an antenna's maximum RF capacity? We are having an antenna system without any written documentation installed on site and it is working more or less fine with the small transmitter installed. (2 folded dipoles at 30m on a 100 w transmitter) We would like to test, how much a new 1.000 W Cybermax would increase our coverage, using the current antenna system. Is there any alternative to just slowly increasing the output power of the Cybermax until the reflected power increases too much?
We have an antenna analyzer (rigexpert AA-600) on site but so far we only used it check the SWR. Can we also use it to determine the max power load of the entire antenna system?
If not, what would be the highest acceptable reflected power reading for a constant operation without risking damage to the antennas, the combiner, the coax or the transmitter?
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Post by ABC FM »

At the first place, high vswr will damage your transmitter, if there is no protection. Then, in extreme case, it will burn the coax. High vswr does not indicate antenna power handling, it indicate impendance missmatch. Max vswr is 2:1 or 10% of nominal power. Now about antenna. Nobody can tell you exact what can your antenna handle. If there is N connecton on antenna, it could be indication that can run at 500w. But it is just indication (who knows what kind balun material is inside, what kind of insulation..). if there is 7/16 connector on antenna, that could mean that rated power is more than 1kW. Same for divider. If it is metal tube with N connectors, perhaps can handle up to 500w. Coax divider usual can handle lower power. Interconnection between divider and antennas is also important. for high power minimum is rg213 or similar. As main coax rg213 can handle up to 700w
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Post by pcs »

One way to find out is to try... at some point it will fail, either arc over, form a short or open circuit.

Any of these conditions is also likely to damage the transmitter in the process.

So... if you have to ask it may be best to buy your antenna from a reputable source.
Best regards,
Marko - PCS Electronics
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