My First Attempt At A Mobile Antenna

[crmzendrgone]

So if I am understanding what is said here
The Ultimate Guide to 11 Meter CB Antennas
your coils are the same as the coils in the base loaded antenna.

 

[W5LZ]

I think 'crmzendrgone' found an answer to his question himself. There might be some very slight differences in the coil because of where it's placed in an antenna, but not much, if any.
- 'Doc

 

[BOOTY MONSTER]

So my question is what do those coils do ..............

http://www.worldwidedx.com/cb-antennas/83417-coil-height-mobile-antennas.html

 

[crmzendrgone]

Ok so in "THEORY" anyone can take a 36' piece of metal and run a cable to it and that can be an antenna?

The reason the are not 36' tall antennas is cause you can have smaller ones that are a proportional ratio to 36' and with the addition of a coil even smaller. Is that the basic idea if told to a 5 year old????(me being the one with a 5 year old mind, lol)

 

[Robb]

Ok so in "THEORY" anyone can take a 36' piece of metal and run a cable to it and that can be an antenna?

The reason the are not 36' tall antennas is cause you can have smaller ones that are a proportional ratio to 36' and with the addition of a coil even smaller. Is that the basic idea if told to a 5 year old????(me being the one with a 5 year old mind, lol)

A three foot long antenna would work IF it has a coil to properly load/'tune' it. In comparison, running a 102 inch steel whip requires NO coil load/'tune'. The coil 'tricks' the 3 ft whip into seeing it as a 1/4 wave/102 inch whip. Does it work as well? No. Does it work? Yes; but with greatly compromised performance.

What Homer has done is made an antenna that is less than 102 inches and made it resonant by including a loading coil. Does it work as well as a 102 inch whip? No. But having a shorter antenna has some advantages, mostly mechanical ones. It won't move around as much when rolling at speed, as well as avoiding low hanging branches that can damage it.

The best 'short' antenna that I've used/heard, is the 5 ft Wilson Silver Load. Those really short/3 ft antennas are a real waste of time and money - IMO. Just because someone sells them - doesn't make them useful. It just fills a niche for those who understand that an antenna is needed and don't understand the practical realities of an antenna that can perform well.

Just sayin . . .

 

[crmzendrgone]

Cool. Thanks for the insight. I starting to understand and get the hang of all this! Yah me.

 

[crmzendrgone]

So HomerBB can I get a part list for that antenna. Not that I am near ready to tackle something like that but interest later, when I know more.

 

[HomerBB]

Thanks everyone for stepping up and helping him to understand what's going on here.
I'll try to make a list of the parts for you sometime later when I'm not on the job.

 

[crmzendrgone]

Thanks everyone for stepping up and helping him to understand what's going on here.
I'll try to make a list of the parts for you sometime later whern I'm not on the job.

Understood and appreciated. Again THANK YOU everyone for the help and info. I was affraid I would get blasted for not knowing anything. But I can tell this is a group of real enthusist, by the willingness to share their knowledge of their hobby. Thanks again.

 

[HomerBB]

The hardest part is working out a mounting piece. I came up with two versions, so I'll share the easiest one. I did it by using an "el" bracket

from the hardware store. I drilled it out with a step bit

so that I could fit a an electrical box hole protector

in the bracket. This I put in the bracket from underneath. I threaded
a 1/2" FPT PVC coupler

onto that from above the bracket. This serves two purposes, to insulate the antenna from the bracket, and to form a means of connecting the antenna to the bracket mount.
I used a brass 1/2" MPT x 1/2" compression fitting

to set the bottom shaft onto the PVC coupler.
the rest of the parts are illustrated on this photo post link:
Post 26
flat aluminum bar.
aluminum tube
Stainless Steel threaded rod
stainless steel nuts
5/8 rod
10-24 set screws
stainless steel whip from old antenna


Ask specific questions and I'll try to answer them.

 

[DoughboyX]

I have a question. The flat aluminum bar and the insulator how long was it and the copper tubing what size was it also and how long. May try this myself but need the measurement. thank......

 

[crmzendrgone]

Nice run down and thanks for the pics.

 

[HomerBB]

Nice run down and thanks for the pics.

No problemo

 

[HomerBB]

I have a question. The flat aluminum bar and the insulator how long was it and the copper tubing what size was it also and how long. May try this myself but need the measurement. thank......

The flat bar is 3/4" x 48"
There are several lengths for the insulator as the antenna changed.
1st - 8" w/3" coil diameter
2nd - 6" w/6" coil diameter
3rd - 4" w/8" coil diameter

Copper tubing changed, too.
The tubing lengths varied from 12" on the bottom to 17" on the bottom
and 12" on the top to 6" on the top. For the shaft the tubing is 1/2 inch copper pipe, not coil. To determine which length of coils and shafts you are interested in just compare the three different antennas and you'll deduce which lengths your to use.

 

[DoughboyX]

Thanks alot HomerBB

That will help me alot.......on a budget and I can build this for around $20-$25 bucks. I will use the larger copper tubing because that's just me. Will use all copper expect the coil and the screws. And my insulator will be on the inside not the outside I will see what happens. Man this is good stuff. And thanks for sharing....op: