No ground plane (NGP) used with ground plane?

[Miescha]

So after way too much research, I'm ready to order my CB antenna (still working on the quad ham deal). After talking with the highly recommended guys at walcottcb.com, I decided on the firestick 4ft firefly (light and flexible for offroad). I went with the mud recommended Firestick SS-174 hood mout (to go next to the factory antenna using existing holes). They had a kit that included the firestick coax cable with the mout, and also recommended a spring mount and quick disconnect.

My only remaining question is regarding a no-ground-plane antenna for the ARB front bumper. I was planning to order a second setup for the ARB just in case I liked it better. For that, the Walcottcb.com guys recommended a no ground plane firestick (pretty similiear setup otherwise). I'm just wondering if I could buy just the NGP antenna and use it in both locations?

Would a NGP antenna perform poorly in a location such as the hood crevis where there is a ground plane (or would it just not have as good of reception as a standard antenna?)

Thanks!

 

[Cruiserdrew]

I can't really answer your question. CB is kinda like yesterday's news.

In general, though, a NGP antenna will be a 1/2 wave antenna, and give excellent performance. If it has a good ground plane it will have some gain. If it's mounted in isolation, it will have no gain but low swr(good). Mounted in the center of a good ground plane, it will have good swr AND just a tad less gain than a real 5/8 wave.

The bumper is a bad place to put it electrically, as you know.

How about a lip mount on the hatch? Diamond K400 3/8 with your wilson or firestick of choice? Then you can sort of have it all, and set it up similar to a good Ham radio install.

 

[lucky dave]

Why front fender?

Miescha

I am also considering where and how to mount CB antenna. Also, will later mount 2m/70cm when get my license.

May I draw on your research? Why did you choose to mount on front fender?

Please keep us (me) informed as to your further research on NGP antennas.

Thanks

Dave

 

[Miescha]

CruiserDrew, As always, thanks for the input. I know the front ARB bumper is a lousy mounting location (even though it works well for many here on mud). I just liked it as a really stout base that couldn't be harmed. This is why I ultimately decided to follow everyone's advice and mount it using a lip mount. I decided on the passenger side hood just forward of the factory am/fm antenna b/c the SS-174 mount can use existing holes/bolts in the hood groove. That location also keeps it out of the driver's line of site.

I know the rear hatch lip is a great location, but I plan to use that later for a quad ham antenna (per my other posts, I recently purchased a Yaesu 8900R quad band radio). I'm installing the CB just for trail use as no other's in my group are using 2m/70cm/10m so I need the CB to keep up.

After even more thought, I'll just skip the NGP antenna for the ARB (it's a lot more expensive anyway). I'll just go with the Firestick FL4 and mount it on the hood groove as outlined above and call it a day.

LuckyDave: I hope the above helps. Basically, I want to reserve the rear of the cruiser for the near-future 2m/70cm/10m ham antenna (probably a lip mount on the rear hatch as used by Romer and others here).

So for the (antiquated) CB, I originally planed the ARB upper mounting tab on the PS (I've seen this quite a bit on Australian cruisers so I figured it was a good idea). Additionally, the ARB tab is very stout. However, after much research, it seems this is a horrible location electronically and the groove of the hood is much better and perhaps just as easy using the SS-174 mount b/c there are already holes/bolts that match up (no drilling).

Sorry for the doubled info, but hopefully 'clear as mud'

 

[RHINO]

theres nothing wrong with a bumper mount for talking in a group on the trail. just get the swr dialed in and your good.

 

[Miescha]

In the interest of completing the story, I received my stuff from Cox CB last night (well, except for the parts that were missing). I opened it up today and got started running cable. Just for the heck of it, I first mounted the antenna on the ARB bar (top mount point) and tried to tune it - no dice.

The SWR readings were WAY in the red zone across the spectrum, and nothing I could do to the tuneable tip made a dang difference. I guess its possible I goofed something when putting the coax connector on the end, but I don't thing so.

I guess I'll move it to the hood groove next to the am/fm antenna tomorrow as suggested here (I purchased that mount and a mount for the door groove in case I wanted to use it at the rear hatch).

Just thought I would verify the outcome for others thinking of the ARB mount. FWIW, I could still pick up and get out just fine, but from what I've read, that level of SWR may actually damage the radio, and will certainly reduce the range.

 

[TrickyT]

...Just for the heck of it, I first mounted the antenna on the ARB bar (top mount point) and tried to tune it - no dice.

The SWR readings were WAY in the red zone across the spectrum, and nothing I could do to the tuneable tip made a dang difference. I guess its possible I goofed something when putting the coax connector on the end, but I don't thing so...

For acceptable results, you need to make sure the shield of the coax is grounded to the ARB and that the ARB has a good ground to the chassis. This means scraping/sanding away the powder coat paint as needed. The fact that the far end of the coax is grounded at the radio is not enough; the antenna end needs to be grounded too.

Notice I said "for acceptable results." You'll never get good/great results with the antenna mounted to the bumper.

 

[Miescha]

Notice I said "for acceptable results." You'll never get good/great results with the antenna mounted to the bumper.

TrickyT: I'm sure your right and it just makes me wonder how good my signal might be if I moved it off the ARB where I currently have it mounted.

I put it there only after I decided I couldn't dial in the SWR anywhere, so might as well leave it where I liked it best. Then I figured out the ground and left it there with the thought that it would work fine for close trail communication.

Interestingly, my first communication was on the way to the park and I was able to pick up another mud member looking for us - from a highway distance of 9-11 miles based on the mile marker location he gave. Not bad given the ARB location. Again, it just makes me wonder how good it could be if properly mounted on the hood groove mount.

But I'll be using the Yaesu 8900R for distance communication long-term anyway (once I get an antenna . . . and a license) so I'll probably just clean up the wiring and leave the Firestick CB antenna on the ARB so I have plenty of distance from the future location of the ham antenna on the rear hatch.

Thanks again for all the help!

 

[Kofoed]

The NGP kit that firestik supplies attempts to "ground" using the coax and the radio chassis. This is different than the vhf/uhf ground *independent* antennae that are actually the proper physical length to be at the 1/2 wave length.


http://www.firestik.com/Tech_Docs/GP-or-NGP.htm