All my 70cm antennas are showing super high SWR

OhSixTJ

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Is that possible? Verified that my mobile NMO antenna is showing a regular (2:1 vs 19.9:1 on a surecom meter). Is it possible that every SMA antenna I have for UHF, including a comet sma-24, is bad? The other antennas are random Chinese antennas so I kind of expected them to be bad...
 
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a417

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or your mount is bad...or your cabling is bad...or your SWR meter is bad...
 

OhSixTJ

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Well like I said, it tested fine with a NMO antenna and the antennas tested fine on 2m.
 

OhSixTJ

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Are you checking SWR on antennas for hand held radios? If so what is your setup?
yes the high readings are on a handheld.
ID-51a with other stock AND comet sma-24 antenna show massive SWR numbers on 70cm. On 2m it’s around 2 for both.

iD-51a > sma female to female adapter > surecom SWR meter > antenna
 

W9BU

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Attempting to measure the SWR of a rubber duck handheld antenna is a generally waste of time. But, that doesn't stop Internet experts and YouTubers from doing it.

You need an anechoic chamber or an antenna test range so that your testing is isolated from other electromagnetic sources or reflections and you need a consistent ground plane similar to that presented by the radio upon which to mount the antennas. At least, that's this Internet expert's opinion. ;)
 
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OhSixTJ

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Attempting to measure the SWR of a rubber duck handheld antenna is a generally waste of time. But, that doesn't stop Internet experts and YouTubers from doing it.

You need an anechoic chamber or an antenna test range so that your testing is isolated from other electromagnetic sources or reflections and you need a consistent ground plane similar to that presented by the radio upon which to mount the antennas. At least, that's this Internet expert's opinion. ;)
It’s not about being an internet expert. They do it with the same meter I have and, while not a perfect test, they get wildly different results using the same method I’m using. Their antennas are testing way better under the same conditions. I guess I just have bad antennas.
 

Hit_Factor

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It's not secret. There are already several threads here on RR on how to do it.
 

wyShack

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Most 'rubber duckie' antennas really are not low SWR. Most handhelds are designed to not be damaged by high SWR. That said the handheld itself is 'part' of the antenna (ground plane). so adding a meter really messes things up. Another item is the number of coax adapters in the path between transmitter and antenna (including the SWR meter). If it works, it works. Duckies do work better than a broken off 1/4 wave :)
 

cmdrwill

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Not to mention "some" handheld radios have 'tricks' built into them to use these antennas, such as so called dual band antennas that are not.
 

wyShack

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Not always a 'trick' -they may have a finial amplifier section that is matched to something other than 50 ohms resistive- with handhelds the design includes the antenna.
 
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