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CB Dipole Antenna

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APK-1

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Springfield, MO
I purchased a dipole antenna from ebay, it is hanging from my ceiling against the outer wall (14' 8") stretched to the corners.
My SWR was just over 5 with the wire stretched turning the corner on the left.

I put a 4" loops on each side (2 on the left, 1 on the right) which shortened the over all length and the SWR dropped to just over 3.

Suggestions...
Should I Add wire to drop the SWR more?
Should I Add wire and stretch it out going around the room or put more loops or longer with loops?
 

APK-1

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I am confined to the dimensions of the room the wall is 14' 8" wide and 8' 6" high. As I said the when looped the wire it dropped the SWR's, so would more loops help?
 

mmckenna

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I am a lineman for the county.
A lot depends on what's behind the wall….

If it's a plaster wall with metal lath behind it, it's going to cause issues.

If it's an exterior wall, then metallic vapor barrier on the insulation will be an issue.

If there is wiring, copper plumbing, metal heat ducts, etc., it's going to be an issue.

Any metal in close proximity to the antenna runs the risk of detuning it. More 'loops' may or may not help. Every install is going to be different. You are going to have to experiment until you find a solution. Usually indoor CB antennas don't work very well. But if it's the best you can do, run with it.
 

APK-1

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I shorten the length on the left side by 12 inches by adding more loops and the SWR dropped under 3. So tried the same on the right and it went back above 3. Returned the right side back to what it was and now back under 3 again
 

jhooten

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Just keep in mind that CB signals are Vertically Polarized.


Maybe yes, maybe no.

Talking to mobiles maybe yes. Wanting to "shoot skip" maybe no. Talking on SSB to another base across town going horizontal can cut down on the interference from the mobiles. On a direct path, as long as both ends are the same, it makes no difference what so ever. Start bouncing signals off of things not so much.
 

Retroradio

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Are you using the radio meter...if so try an external meter.
Where is it at its lowest SWR? That “channel” determines weather you have to lengthen or shorten. Look up adjusting dipoles on the net for info.
14’ seems odd, a double bazooka Antenna is about 17’ and cannot IIRC be tested with an Antenna anylzer a SWR meter is required.
A CB dipole would be about 18’ etc.... and an anylzer or SWR meter can be used.
Same length on both sides is the way they work.

Good luck :)
 

APK-1

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Are you using the radio meter...if so try an external meter.
Where is it at its lowest SWR? That “channel” determines weather you have to lengthen or shorten. Look up adjusting dipoles on the net for info.
14’ seems odd, a double bazooka Antenna is about 17’ and cannot IIRC be tested with an Antenna anylzer a SWR meter is required.
A CB dipole would be about 18’ etc.... and an anylzer or SWR meter can be used.
Same length on both sides is the way they work.

Yes, I am using a external SWR Meter.
Channel 1 is approx 2.6 and Channel 23 is 2.7, actually about the same.
I did google searched on Dipole High SWR's and that lead me to a guy who looped his wires and had success. My SWR's were over 3 starting with it stretched out full length. I shorted one side by looping and they dropped to under 3, so I did the same to the other side and they jumped back up over 3.

I bought a second Dipole off of Amazon a Falcon 6 Meter Dipole 1/2 Wave Amateur Ham Radio Base Station Antenna and took down first one I bought off of ebay. Put up the Falcon, SWR's were 10. So went back to the ebay one and sent the Falcon back to Amazon.
 

Retroradio

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A good article that might be of interest As it details ( towards bottom of page) how to properly trim/lengthen/fold back the antenna wire to adjust SWR.

Always trim/adjust equal SMALL amounts.

The calculator link will give you a good idea of the length it should be. When building one its a good idea for out be too long to start with then adjust.

West Mountain Radio - Antenna Calculator (That’s Ch19) I usuallset them for ch20...

What type of coax are you feeding it with. Bear in mind that internal to a house and not up to height will have a great impact on the SWR.

I recently built a double bazooka antenna for ch19 out of speaker wire and hung it on my ceiling.with some trimming I had it down to about 1.5-1. The local stations that normally get me a 10+ On the man in antenna had me about 7-8 S units.

Good luck :)
 

prcguy

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Why would you buy a 6m dipole for CB? Its only about half the size it needs to be for CB and wouldn't even come close to working.

A dipole stretched out is usually not a good match to 50 ohm coax because it can be as high as 70 ohms when its up in the clear. If you make the dipole an inverted V where the coax is at the bottom and the wires go up a wall at a 45 deg angle or 90 deg to each other it will usually match just fine to 50 ohm coax.

As mentioned before, if there is wiring in the walls near the antenna or if the building is stucco with metal lath in the walls or similar, it will never match up and work right plus the building could be a big metal shield blocking signals.

Yes, I am using a external SWR Meter.
Channel 1 is approx 2.6 and Channel 23 is 2.7, actually about the same.
I did google searched on Dipole High SWR's and that lead me to a guy who looped his wires and had success. My SWR's were over 3 starting with it stretched out full length. I shorted one side by looping and they dropped to under 3, so I did the same to the other side and they jumped back up over 3.

I bought a second Dipole off of Amazon a Falcon 6 Meter Dipole 1/2 Wave Amateur Ham Radio Base Station Antenna and took down first one I bought off of ebay. Put up the Falcon, SWR's were 10. So went back to the ebay one and sent the Falcon back to Amazon.
 

Retroradio

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Good call prcguy, I missed the fact that the Falcon was a 6m dipole.

If the OP looks at the links I attached the general requirements of an 11m dipole will help him out. A bit of wire and there easy to build.
Ive run dipoles inside, do they work...yes. Effectively....not so much.
 

WB9YBM

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I purchased a dipole antenna from ebay, it is hanging from my ceiling against the outer wall (14' 8") stretched to the corners.
My SWR was just over 5 with the wire stretched turning the corner on the left.

I put a 4" loops on each side (2 on the left, 1 on the right) which shortened the over all length and the SWR dropped to just over 3.

Suggestions...
Should I Add wire to drop the SWR more?
Should I Add wire and stretch it out going around the room or put more loops or longer with loops?

check out some of the formulas available on line to make sure you have the right length. if the SWR is still off it could be because it's too low to the ground (references I've seen say something about best performance beginning at 1 wavelength above ground). Also see if there are other metalic objects near it that could interfere (like electrical conduit in the wall).
 

APK-1

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>What type of coax are you feeding it with.<
RG58A/U 9ft

>if the building is stucco with metal lath in the walls or similar<
No stucco, wood studs, vinyl siding.

>eBay Dipole<
Half-Wave Base Station Dipole Antenna CB Radio Band 11 Meters
17 feet, 4.2 inches (17' 4.2") in total length, which comes to 8 feet, 8.1 inches (8’ 8.1”) on each side.

I equaled the lengths (5' 4") on both sides of the Balun, then played with looping the extra wire (left - two 7", right - one 11") and was able to get the SWR's down Channel 1 = 1:3 and Channel 23 = 1:5. Channel 40 = 1.5.5

20200329_200153.jpg

I tried different size loops in different places but could not improve upon what is above.
 

rivardj

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If that antenna is bare copper wire and the wire is touching in each loop you are shorting the loops out which is creating a very short length antenna.

Run each side straight from the balun to whatever you are using now to support the ends and then let the ends hang straight down toward the floor. You will need to put a 90 degree bend in the wire, it does not have to be a sharp bend.
 

APK-1

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Not bare wire. Coated wire is supported by 3M Command plastic hooks.

>Run each side straight from the balun to whatever...and then let the ends hang straight down toward the floor.<
This setup jumped SWR's to 5 on Channel 1 & 23.
 

Recka79

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I have good luck with my Falcon dipole I got off of Amazon back in February. I have it mounted in my attic in an inverted V ^ I have the SWR close to perfect by rolling each end once or twice. On LSB with a peaked Uniden Washington I've talked to people 20 miles away. I've also had luck hundreds of miles away the few times skip has rolled in this winter/spring. My advice is to make sure the wires are pulled tight and make sure your coax isn't pinched anywhere.
 

russbrill

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Jan 5, 2020
Messages
380
Location
Sacramento, CA
I purchased a dipole antenna from ebay, it is hanging from my ceiling against the outer wall (14' 8") stretched to the corners.
My SWR was just over 5 with the wire stretched turning the corner on the left.

I put a 4" loops on each side (2 on the left, 1 on the right) which shortened the over all length and the SWR dropped to just over 3.

Suggestions...
Should I Add wire to drop the SWR more?
Should I Add wire and stretch it out going around the room or put more loops or longer with loops?

Do you have attic access??? A CB Dipole (depending on the roof) could be installed as an inverted-V hanging from the rafters...

Duh, just noticed the Recka79 post...
 
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