Edit: Despite a lot of silly comments making jokes, which I think is a disservice to the hobby anyway, there were some kind comments with very good suggestions. I'm very grateful for that.
I haven't tested it yet, but this antenna was suggested and seems to be exactly my use case (thanks u/killrade), I'm buying it now (October 3rd), but it will take a while to arrive in Brazil. As soon as it arrives, I'll try to test it and bring the results to this post.
Thank you very much to those who dedicated enough time to check that I only wanted a minimally viable COTS antenna for reception in the CB band, and not to transmit to the other side of the world...
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Original post:
Hi everyone,
I'm looking for recommendations for a CB antenna no longer than 30 cm.
And before the usual replies start:
Yes, I know you can't change physics.
Yes, I know CB is in the 11 m band and that a proper antenna is around 2.4 m.
Yes, I know anything much shorter than ~1.2 m is considered "useless" for CB.
Yes, I know about loading coils, efficiency, ground planes, SWR, radiation resistance, etc.
I genuinely don't need a lecture about that.
To be completely honest, I probably know more about the antenna theory behind this than the average person here. My thesis was in satellite telecommunications, including the development of a ground station and an onboard communications system using SDR.
I just want a damn antenna that works reasonably well enough for my specific use case.
My goal is to have a CB radio in my car mainly for listening when traffic is backed up, which is pretty common on the roads I travel every week here in Brazil.
My priority is discretion, not transmission performance. I'm perfectly aware that a 5 W CB radio isn't going to do miracles anyway, especially with a tiny antenna.
For actually talking to people traveling with me, we already have VHF/UHF radios — and yes, we have the proper licenses to transmit on those frequencies.
For CB, I already have a proper base station at home.
What I want from the car setup is simply to listen to truck drivers farther ahead in traffic and get some situational awareness:
- Why is the road blocked?
- Is there an accident or some other problem ahead?
- Is it worth taking another route?
- Is it worth stopping at a gas station/rest stop, getting some food, etc., and waiting for traffic to clear before continuing?
So I'm not trying to build a 30 cm miracle antenna that outperforms a quarter-wave whip. I just want the best practical option within that physical constraint.
If that means using a short loaded antenna, fine. If a small magnetic/electric loop or some other unconventional solution makes more sense for receiving, I'm open to that too. If I need an LNA + band-pass filtering on the receiver side to compensate for the poor antenna efficiency, also fine.
What I don't want to do is model/optimize an antenna in HFSS or order five different antennas from AliExpress, wait 1–2 months for each one, measure them on a VNA, install them in the car, discover that the advertising was complete bullshit, and repeat the whole process.
So, with all of that out of the way:
What compact CB antennas (≤30 cm) have you actually used, and which ones would you recommend specifically for receive-only / mostly-receive use in a car?
I'm much more interested in real-world experience than in hearing again that 11 m antennas are supposed to be 2.4 m long. I already know. 😄