102" stainless whip

[loosecannon]

i do tend to get a bit "spouty" when it comes to certain subjects, and looking back at my post; i did kinda jump all over your @#$% for what could have been construed as a funny comment.

im cool if you're cool.

back to antennas. the standard "102" whip" used to come in either a stainless steel or fiberglass version.
the fiberglass tended to be a bit stiffer and retained more of its vertical stature when driving.

the fiberglass version was simply a 14-16ga. (maybe even 18ga!) copper wire embedded in a fiberglass shell.
no coils, no helical winding, just a vertical wire.

my contention, from what little i think i understand about it, is that the fiberglass does indeed introduce a significant velocity factor, and that is why the copper wire/fiberglass "102" whip" is actually 96" long.

yes, i am kind of guessing here. the way i see it, its like making a dipole out of insulated as opposed to uninsulated wire.
the insulated wire would be shorter.

if i am off base i am certainly willing to learn, but i need to know the "why's" before i am convinced.
LC

 

[jazzsinger]

There is a very small VF factor difference between the SS and copper radiators, but not enough to account for a 6% difference. While there is a significant difference between these metals when used as feed-lines, when compared as radiators, there is not much difference. The fiberglass used used in the above mentioned antenna is not in a very intimate contact with the radiator and so does not have an appreciable effect on the VF.

The type of antenna loose cannon was referring too is a copper wire running through the middle of a fibreglass tube (basically supporting it in a vertical plane) which is in very intimate contact with the wire,which is why the velocity factor is more affected by the fibreglass than by the difference in metals,which accounts for the 6% length difference.

the type of antenna your referring to sounds more like a firestick type helically wound antenna,where the wire is wrapped round the fibreglass and covered in shrink wrap,the wire length on that will be much more than 96" or 102" for that matter,as its basically a continuous coil that tunes out reactance whilst radiating,in which case the coiling will have a huge effect compared to velocity factor caused by either the wire type or fibreglass/shrink wrap.

 

[Peddler]

I stand correct on my ideas of the fiberglass antenna...as far as this going to the CB section, a 102" antenna can be used on any band so this is as good as anywhere.

Ham, CB as well as SWL are all a hobby and all have equal acess as well as opinions.

Thanks

 

[wavrider]

I stand correct on my ideas of the fiberglass antenna...as far as this going to the CB section, a 102" antenna can be used on any band so this is as good as anywhere.

Ham, CB as well as SWL are all a hobby and all have equal acess as well as opinions.

Thanks

Yes it can be used with a tuner for different bands, I use one for 10 meters mobile, and with the rig tuner it has no problems tuning 12 meters.

 

[76Q]

I have a vintage white 102" fiberglass whip, same length or very close to a 102" stainless steel tapered whip that I have. Both are my highest performing antennas, bar none! so the 102" fiberglass whip does come in 102" version. It tunes practically the same as my stainless steel one. I use both of them with Hustler spring, 1 inch spacer and hustler quick disconnect on a ball mount. sounds long at 109 inches, but the base mounting structure has a lot to do with why this slightly longer length works for me. Remeber the radiator element is only 1 component that affects your antenna resonance. The ground plane, mounting structure and anything in the way will affect its resonance. So YMMV on length needed.

 

[office888]

Yes it can be used with a tuner for different bands, I use one for 10 meters mobile, and with the rig tuner it has no problems tuning 12 meters.

Its my understanding, if you have an automatic tuner mounted VERY close to your 102" whip, you can tune up on 40m as well! The efficiency is pretty low, but with 100w, you'll still get out fairly well.

 

[jazzsinger]

1. Fiberglass has a velocity factor because it's an insulator.
2. Uninsulated, bare wire doesn't have a noticeable velocity factor.
3. So any velocity factor associated with a fiberglass antenna is because of the fiberglass.
That's amazing. Totally wrong, but still amazing. I'd ask where that came from, but I'm not too sure I wanna know.
- 'Doc

1.Fibreglass wrapped around a conductor has a velocity factor because its a dielectric.

2.Uninsulated bare wire does have a velocity factor in air,Air is the dielectric,which is why antenna's are trimmed between 2-5% (depending on metal used) from what their measured physical wavelength would have been.


3.Exactly and any exposed metal/uninisulated antenna with a velocity factor in air is due to the Air

 

[W5LZ]

office888,
You understand correctly, it's certainly possible to use a 102" whip that way. You are also correct in that it wouldn't be a very efficient radiator at all. Just a little different that what you described, there are a bunch of screwdriver antennas that work on 40, and 80, meters using a 102" whip (usually slightly shorter than 102", but that's just to keep the over all height down). 'BugCatcher' type antennas, same way.
- 'Doc

 

[W5LZ]

jazzsinger,
Are you really sure you want to state it that way?
- 'Doc