top load vs center load antenna

22.62 feet of wire assuming it's straight wire.
Once you start putting a coil into it it's going to drastically change you might need 60 feet of wire per side by the time you're done miniaturizing it and the coil losses are going to be so enormous it might not even be worth doing.

 

I use a 5' fire stick and it works great. I get good reports all the time.

 

And I run a galaxy DX 33hp2.

 

Even a straight wire 5/8-wave antenna will not have a 50-ohm feed point impedance. Hence the impedance transforming network at the base of a typical VHF or UHF NMO style antenna. Similarly, 5/8-over-5/8 wave UHF has an impedance transforming base AND another network at the top end of the lower whip section ro feed the upper whip section. And while the single 5/8-wave has a theoretical gain of +3 db, the 5/8-over5/8-wave has only about +5db because of the predictable loss from the somewhat compromising effect of the upper "coil" on the lower element.
I'm only using VHF & UHF antennas for this example because the relatively shorter wavelengths allow for practical *actual* gain mobile antennas.

A quarterwave antenna at 150 Mhz is around 18-19 inches; at 450 Mhz is around 6 inches. Predictably, 5/8 wave at 150 Mhz is around 18+18+9 inches, or about 45 inches (+/- for actual freq.) 5/8 wave at UHF is about 6+6+3 inches, or about 15 inches.

A 5/8-over5/8 wave is impractical at VHF ("2 Meters ham band") because of a needed height of around 94 inches and the same wind drag issues and need for a counterpoise surface that affect CB antennas, although a 2M antenna only needs about a 20 inch radius around the feedpoint. At UHF, though, a 5/8-over-5/8-wave is only about 32 inches in length at resonance, and with a required counterpoise of only about 7 inches, it's completely workable.

Now, scale those dimensions up for CB by substituting about 108 inches for a quarter wavelength, and it quickly becomes evident that, despite the packaging & advertising hype, a true 5/8-wave CB antenna *must* be 108+108+54 inches, 270 inches in length --- about 22.5 feet -- plus an impedance transforming network.

Since coils don't radiate (save for a helix), any 4' or 6' (or any length) antenna that purports to be a 5/8 CB mobile and is shorter than a two-story house's height is....ummmm.....fooling their customers.

Thus endeth the lesson. Further affiant sayeth not.

Sorry for the long post, my tablet finger is now 1/2 inch shorter.....

73

 

YEAHHHH..What handle bar said.......*whispers* whats all that stuff mean??..

 

Unfortunately, and somewhat counterintuitively, so do an awful lot of hams. While I'm glad that the somewhat easier ham license exams are a bit easier to study for, and no more Morse ability required, have helped to swell our ranks, the number of "applicance operators" has somewhat diluted the technical competence of the overall body of hams.

Not all bad, of course; a whole lot of hams bring in their modern-ish multimode gear to our shop to get simple (well, to the trained folks) things fixed --- things like mic gain, TX deviation, TX/RX offsets, and the like. So CBers certainly don't have a monopoly on being lids, and everyone pays the same at our shop.

At the risk of sounding smug, I often retreat to the Extras-only portions of the phone and CW DX bands. I just occasionally need a "brain reset" to make sure I haven't completely lost my storehouse of useless knowledge

Toodles & 73,
-- Handlebar in NC --

 

<whispering back> There's no such thing as a 5/8-wave antenna for a CB mobile that's shorter than a 2-story house. Shhhhhh.......

73

 

looks like a k40 antenna ??? or a funky made I mean monkey made

 

I'll be buying a massive no b.s. antenna this week I'll need the best mount and stud I can find... if you have any suggestions or ideas rabbi I'm looking and listening. .. thanks