Antenna Tuning

[jimbr1]

I have a question about antenna tuning. I'm using a small tunable whip antenna. When tuning, I can get as low as about 1.2 to 1. If I tune it low for channel 19 or 20, by the time I get to channel 1 or 40, the SWR is a little over 3 to 1. My question is, if I use an antenna matcher, will it lower BOTH high SWR ends simultaneously (channel 1 and 40) or just one end, either channel 1 or 40? If I need to re-tune it when I change channels, could I just tune the antenna itself for the high or low end (say lowest SWR on channel 40) and use the matcher to tune for lowest SWR on channel 1? I'm just looking for information from personal experiences as I have done research which so far has not really answered my questions as I am not looking for antenna recommendations, only tuning experiences. Any info would be appreciated.
Cheers

 

[WouffHong]

Swr

I if I use an antenna matcher, will it lower BOTH high SWR ends simultaneously (channel 1 and 40) .
Cheers

Negative - each extreme will require retuning as you have probably noticed. The reactance of the antenna will change as you move from Ch1 to Ch 40 and require retuning at points that are over, say, 1.5-2.0 SWR
Da Wouff

 

[jimbr1]

I was hoping for a bit of magic...now back to reality....thanks for the info...
Jim

 

[JayMojave]

Hello Jimbr1:

Don't sweat the SWR there, those short antennas will have a narrow SWR bandwidth. The radio will work just fine with those higher SWR's at the band edges. Is not a problem GI!

Jay in the Mojave

 

[jimbr1]

thanks Jay!

 

[sloop]

Ant. Tuning

Jimbr1...I agree, don't sweat the high SWR at the band edges. Tune your antenna with ch 19 (freq. wise it in the middle of the 40 chs.). You should not see much SWR difference across the chs.

 

[rfking123]

I have a question about antenna tuning. I'm using a small tunable whip antenna. When tuning, I can get as low as about 1.2 to 1. If I tune it low for channel 19 or 20, by the time I get to channel 1 or 40, the SWR is a little over 3 to 1. My question is, if I use an antenna matcher, will it lower BOTH high SWR ends simultaneously (channel 1 and 40) or just one end, either channel 1 or 40? If I need to re-tune it when I change channels, could I just tune the antenna itself for the high or low end (say lowest SWR on channel 40) and use the matcher to tune for lowest SWR on channel 1? I'm just looking for information from personal experiences as I have done research which so far has not really answered my questions as I am not looking for antenna recommendations, only tuning experiences. Any info would be appreciated.
Cheers

A rule of thumb for you. The higher the frequency, the shorter the antenna. CB channel 1 is: 26.965; CB channel 40 is 27.405. A difference of 1.440 Mhz. If you trim back too much channel 1 may jump in SWR, and visa verse. It is always a compromise but if you tune very carefully, you can get a good SWR for both channels 1, and 40. It is a "knack," without having to resort to tuners, and cutting.

 

[jimbr1]

Thanks for the replies- the antenna I'm using is a small whip outside on a metal air conditioner housing. It is easily tuned but very narrow as describe previously. My only other option is an indoor dipole- may have a better match across 11 meters but, being inside- I don't think it will perform as well as an outdoor antenna- even a small one.