Poor range despite setup

[tekinozbek]

To be clear: I'm not expecting exceptional performance with my setup, but I'm expecting more than what I'm getting...

On the transmitting end: my 2' antenna is on the hood on a Diamond K400 mount and the SWR around ch. 20 is about 1.3, going up to about 1.6-1.7 at the edges of the bands.

On the receiving end: 4' antenna on top of a large solid sheet ground plane and 4x 102" copper cables radiating outwards to extend the ground plane.

I stop receiving after 1km on SSB on Ch 20... What am I doing wrong?

 

[merlin]

I don't know of a 2 foot CB antenna. What kind is that.
4 foot is 1/8 wave and tuned should work at least acceptably.
Your ground plane sounds OK if the copper cables are not touching any metal.
How high above ground is it ?
What radios are you evaluating this with and their power output ?
Are you receiving other stations with either setup ?
Can they hear you ?
More info is needed to resolve this.
Cheers

 

[mmckenna]

To be clear: I'm not expecting exceptional performance with my setup, but I'm expecting more than what I'm getting...

On the transmitting end: my 2' antenna is on the hood on a Diamond K400 mount and the SWR around ch. 20 is about 1.3, going up to about 1.6-1.7 at the edges of the bands.

A 1/4 wave CB antenna would be about 108 inches long. Any antenna shorter than that is going to be loaded in some fashion, and that will result in lower performance.
Trying to cram 8 feet of antenna into a 2 foot whip is going to give you exactly what you are seeing, poor performance.
And mounting that antenna on a compromise mount on the side of a ground plane is going to make whatever energy it does radiate head off mainly in one direction (away from the vehicle body). So, you have a lot working against you, and 1km of range would be expected under most conditions with a setup like this.

The low SWR just means that not much energy is getting reflected back, which is a good thing, but it doesn't translate into good performance. A 50Ω dummy load will show near perfect SWR, but won't radiate energy.

You need a more efficient antenna at minimum. Mounting a more efficient antenna in the center of the ground plane will help, also.

On the receiving end: 4' antenna on top of a large solid sheet ground plane and 4x 102" copper cables radiating outwards to extend the ground plane.

I stop receiving after 1km on SSB on Ch 20... What am I doing wrong?

4 feet is a bit better, but I think your issue is the 2 foot antenna on the other end.

There may be other issues, but the information you have provided points to a very limited performance antenna system on your vehicle and a less than ideal antenna on the base.

 

[tekinozbek]

I realize SWR doesn't translate into good performance; I indicated the values to show that not much of the SSB power is being lost.

I don't know of a 2 foot CB antenna. What kind is that.
4 foot is 1/8 wave and tuned should work at least acceptably.
Your ground plane sounds OK if the copper cables are not touching any metal.
How high above ground is it ?
What radios are you evaluating this with and their power output ?
Are you receiving other stations with either setup ?
Can they hear you ?
More info is needed to resolve this.
Cheers

Firestik makes 2', 3' and 4' antennas. The radio is President McKinley. The receiving station antenna is about 8' off the ground, and the copper cables are not touching anything else (they are insulated cables and their ends are sealed).

I do receive other stations, mostly the 1kW super bowlers, and I have had one contact in Nevada (from Ontario) hear me month or so ago.

As I said, I don't expect much from the 2' antenna, though I expect more than 1km since that is about the same range I get with rubber ducky handhelds.

 

[mmckenna]

There are a few companies that will make stubby antennas like that. Reason is there's demand for them.
But they are not good performers. When conditions are really good, you might be able to make some contacts, but it won't be consistent.

It's been a long time since I used CB, but when I did, I ran a Larsen NMO-27 whip mounted dead center on the truck roof. It worked pretty well.
Long before that, I wouldn't run anything less than the 48" antennas. Like I said, trying to cram 8 feet of antenna into a 2 foot whip isn't going to perform very well.
If SWR is good, it's likely your connectors and cable are good.

 

[AC9BX]

"plane" is the part of ground plane people often miss. A big piece of metal may be a counterpoise (a place for radio signal current to flow into) but it may not be a good ground plane. The plane is a critical part of a ground plane antenna.
A ground plane need not be any larger than the vertical section, although it certainly may be. The size of the plane (and angle relation to the vertical) will affect the feed point impedance. The vertical section should sized and tuned for the frequency to be used. 2 feet just isn't enough for efficiency at these frequencies.

Same as a rubber ducky? That's about what I'd expect from a 2 foot antenna on 27MHz CB.
Good SWR doesn't indicate power isn't being lost. Like mmckenna said, a dummy load will show (near) perfect SWR while (near) ALL the power is being lost. It's only an indicator of how the antenna and feed line match the impedance of the radio. Lossy cable will lie to you about the antenna. Exactly the right length of cable will lie to you about any mismatch. (The ol' 17 feet magic number of CB) Using specific lengths of the wrong cable is done intentionally sometimes for the purpose of impedance matching.

Why 2 antennas? Why bother with the 2 foot when you have a much better option, the 4 foot?

 

[tekinozbek]

Why 2 antennas? Why bother with the 2 foot when you have a much better option, the 4 foot?

The 4' looks somewhat ridiculous on my SUV (not to mention, it doesn't fit in the garage).

 

[AC9BX]

The 4' looks somewhat ridiculous on my SUV (not to mention, it doesn't fit in the garage).

I get that. That's the way it goes. And it's why the 2 foot model exists. Imagine an 8 foot whip. Notice the truckers with the crazy antenna with giant coil leaned forward 45 degrees. It's silly. Unfortunately, clamped to the mirror of a truck cab is about the worst place to install a 27MHz CB antenna.

 

[mmckenna]

The 4' looks somewhat ridiculous on my SUV (not to mention, it doesn't fit in the garage).

You'd need to decide if you want looks or you want performance. Like I said, you cannot cram 8 feet of antenna into a 2 foot whip and expect it to work like an 8 foot antenna.

You are not the first one to be frustrated by this. You won't be the last. There is no easy solution. Laws of physics at play here, and us mortals don't have permission to change them.

 

[2IR473]

“what am I doing wrong?”…

If your base antenna is only 8’ off the ground, and is just a 4’ mobile antenna, then I would start there. If you have any other options for mounting a base antenna, you should consider them. Perhaps seeking a 102” whip to replace the 4’ whip might be an option, but I don’t think this current setup will work well for you.

As for the 2’ mobile antenna, I run a 2’ K40 SF-200K as a “daily driver” antenna on my truck, and I am quite pleased with the performance. This is my choice for a low profile CB antenna. I have run many, many antennas over many, many decades. I am not disputing the physics that have been stated above, but I can tell you that a 2’ CB antenna can provide some decent performance…with the usual caveats.

The biggest caveat is…the station receiving you has to have a good antenna ! I can work a friend who is 23 miles away, but his 5/8 wave base antenna @ 40’, along with his Anytone AT-5555N2 are doing the heavy lifting. And for my part, I am running an Anytone AT-6666 in the truck to provide more output power, to help compensate for the short antenna.

I use Diamond and Comet mounts, and have them properly bonded to the vehicle frame, along with other parts of the vehicle, in order to achieve good bonding. This is an important component for a properly working mobile setup. All mobile antenna installations are a compromise. We need to do some work to lessen the losses.

I can work back to my home from distances of 5-10 miles (SSB), depending upon the terrain, which is rolling hills here. But my base antenna is also compromised, as I have my base antenna in my garage attic, which is about 15’ above ground level.

The antenna is an old 1/4 wave (8’ 6”) ground plane which has solid aluminum radials, so I can gently bend them to a nearly 90° angle, in order to fit the antenna in my 10’ attic space. Not ideal since the radials should be at a 45° angle, but it is a working compromise. I once tried using a Tram 1499 3’ tall CB antenna at one time, and I only got about 2-3 miles range. Bigger is better…when it comes to CB antennas.

After 46 years of experimenting with antennas, I am still trying to perfect the imperfect antenna. Keep messing with your setup. There is a lot to screw up…I know from experience. You can definitely get better results than what you are seeing now.

 

[tekinozbek]

Guys... I do understand all of this. I know that my setup is not ideal, nor do I require it to be.

What I do not understand is that I'm getting the same performance out of a 2' transmitting antenna and 4' receiving antenna on SSB as I do with 2 handheld Cobras on AM with rubber duckies with one of them being indoor. So then why would anyone ever buy a 2' antenna? Just throw the rubber ducky on top the car on a mag mount.

This problem is indicating to me that there's something else going on. The usual "get a longer antenna" discussion, which I've read on many forums ad nauseam, does not really answer my question.

Perhaps it's to do with the coax, the mount or the transmitter itself. Not sure how I would go about testing the coax and the mount.

 

[KANE4109]

Just another opinion here.........

Any "short" antenna is a "compromise". By itself it will not resonate/tune at the proper frequency for the intended band.
In order to MAKE it "tune to the band" you add reactance... usually inductance in the form of a coil since a short antenna seems to exhibit capacitive reactance. So you add inductance in an attempt to "tune the capacitance". So now you have a tuned circuit with a shortened whip. The reactive elements don't radiate! The only part that radiates is the straightest part of the whip. If this is a fibreglas "Firestick type" antenna look closely. Under the covering you typically see windings. At some point the windings are tight together.... at others the winding is loose and just spirals up the fibreglas shaft. The tight windings are the inductance added to force the tuning to the band... to make your radio happy. But the only part of that antenna that radiates is the loosest part of the winding. I am just guessing..... but I'd bet there isn't much of that 2' antenna that is loosely spiraled... and that is the only part of the antenna that actually radiates signal. So yes the antenna may be 2 feet long.....but I think that the actual part of the wound wire that radiates is shorter than that. And that adds up to "inefficiency". That little portion of the 2' antenna that is radiating will never be as efficient as a true quarter wave whip. Any "short" antenna is a "compromise".

As to the question..... "why do they make them?".....

Because there are those who either by choice or circumstance... have to live with the compromise. They want to have CB capability but cannot (for whatever reason) commit the space/size required for a "more full length" antenna. I don't imagine that they sell all that many of them as it is fairly popularly known that a more efficient... more resonant antenna is longer at 27 Mhz.

I once had a "back of the set" antenna made by Radio Shack and I kept in on a base radio on my nightstand. I know that it did not receive well,,,,but it DID pick up signals in my neighborhood. What I do know is... it DID tune up to about 1.4 to 1......and with a stock radio... you could not hear it at the end of my block. With that, I just had to be happy that I could sandbag... and hear people in my immediate area.

I am not sure where the expected distance of 1 km came from... but the fact is... that "compromise antenna" may just not do it.
People have been using mag mounts and quick-release adapters for years for this very reason. So that they could use a longer more efficient antenna and yet quickly remove that antenna and stow it so that they can enter a garage.

 

[Cognomen]

Since you have a fibreglass antenna, make sure that the stepped white insulating washer is present between the base of the antenna and the metal grounded mounting surface, or you'll have a short. Some people over-tighten the antenna or whack it on something, which can crack the washer, and then the washer falls out, which makes the antenna loose, and when it gets tightened it becomes shorted.

 

[mmckenna]

This problem is indicating to me that there's something else going on. The usual "get a longer antenna" discussion, which I've read on many forums ad nauseam, does not really answer my question.

Well, there is a reason you keep hearing the same thing:

It's because it is true.

As for your question, you asked:

What am I doing wrong?

Well, first issue was that you have a low efficiency antenna on a compromise mount. That alone is known to greatly impact performance.

There may absolutely be other issues, but you have not provided enough information for anyone to do more than point out the obvious. We're usually very happy to help, but it's hard to do without the details.
SWR alone doesn't tell you a whole lot. The issue you noted about not being able to get past 1km tells us a bit more.
Usually a decent SWR and poor performance indicates a low efficiency antenna, which you have.

As for other possible issues, it's not likely a short in the mount, as that would usually be indicated by a very high SWR that cannot be tuned out. There is a slight chance that the length of coax is hiding a high SWR issue, but we don't have enough info. Likely not the issue based on the cable if you have the 38C version mount, which isn't a multiple of 1/4 wavelength on CB

So, what would greatly help us is for you to give us some exact details, and bonus points for photos.

Do you have this antenna mount? Diamond® Antenna ~ K400-3/8C Trunk/Hatchback Mount
If so, and you didn't disassemble it, it should be good. Often what happens is some will install those 3/8x24 mounts and get the insulating bushings in the wrong place. That can result in the center conductor getting shorted directly to the mount.

Did you tighten down the set screws on the base enough to make contact with the sheet metal? Actually through the paint and making a good electrical connection.

Did you make any changes to the coaxial cable?

Do you have a multimeter that you can use to test for continuity/grounds?
Do you have an EXTERNAL SWR meter?
Do you have a 50Ω load that you can use to test the transmitter output power?
Do you have the RF gain turned all the way up?

Same questions you can answer for your base setup, since there could be issues there also.

Again, bonus points for photos.

​

Perhaps it's to do with the coax, the mount or the transmitter itself. Not sure how I would go about testing the coax and the mount.

See above.

Do you have a multimeter? Do you have an external SWR/Power meter (yes, I know the radio has one built in, but you want to confirm it is accurate and you want ot test transmitter power output at the antenna connector.
Do you have a 50Ω dummy load?

 

[KC1SHA]

I have been having the same issue as the OP (tekinozbek), i.e. poor reception. I finally figured it out. One of the knobs is labeled RFG (RF gain) - if you turn up this gain your receiving range expands. Now I have good reception. It is great that you can turn this up or down depending on the signal being received. Now, I am liking this transceiver. It has some great features.