centerload or base load

[hotrod]

that is the question. i know ive read that centerload mobile antennas are slightly better than baseloaded ones
question is by how much? has anyone ever tried a comparison?ive heard many different opinions on this
ive thought about doing one myself

 

[Robb]

You didn't mention 'top load' antenna in that. . .
Just saying is all . . .

 

[Needle Bender]

I believe the base loaded tends to have a higher TOA than a center-loaded.
If you travel a lot of mountain roads you might prefer the base loaded for getting up & over ridges, but for longer "ground wave" (Donald is cringing! - lol) I've always had better luck with a center-load. Hated the top loaded I tried.

 

[hotrod]

yes robb you are correct! i didnt put top loads cause when i put a 5 foot wilson silverload against a 5 foot wilson 1000 baselod if there was any differences i couldnt tell. though the silverloads were inexpensive.NB im mostly interested in long local talking without using a 102 whip or high wattage. the way i understand it getting the coil higher than the roofline is the key. which is why i ask bout a centerload.

 

[M0GVZ]

Getting the antenna on the roof, using a fixed mount and doing bonding will improve your signal far more than the difference between base, mid and top loading. If you're not having to cut down your antenna to get the SWR down then you're usually not running an efficient system so both transmitted and received signals are weaker than they should be and you usually get increased noise as well. On my fully bonded car I usually find I'm cutting 3-4 inches off the whips.

 

[midnight special]

from what we were taught 40 years ago center load and top load is more effecient,,, top loaded and center loaded was more for trunk mounted antenna setups,,, i run a 102 inch whip on my toolbox on my truck but if i had a choice i would run a top load or center load on it,,, but prefer the whip,,, on my blazer i ran a wilson 5000 trucker on the luggage rack,,, it worked ok but i got afraid it was gonna pull the rack off in the wind so went and hard mounted a base load wilson 5000 in the middle of roof,,,, i couldnt tell no difference,,,, i did switch out a wilson 1000 that was about 25 years old and seemed to recieve better,,,but the boy i borrowed from wouldnt sell it,,,,

 

[Robb]

Most of the fiberglass CB antennas are top loads - IIRC . . .

 

[rabbiporkchop]

that is the question. i know ive read that centerload mobile antennas are slightly better than baseloaded ones
question is by how much? has anyone ever tried a comparison?ive heard many different opinions on this
ive thought about doing one myself

It depends on the vehicle and the mounting location. Center load is ideal but unfortunately nobody seems to make a center load antenna for a tractor trailer so you pretty much have to make one yourself from scratch like these. These would work great on the roof of a car or truck but unfortunately they would also rip a hole in your roof if you hit a bird at 65 miles an hour.

A center load on a tractor trailer still won't perform anywhere close to how this bottom load performs on my Chevy Tahoe though.

 

[fourstringburn]

Center load is ideal but unfortunately nobody seems to make a center load antenna for a tractor trailer so you pretty much have to make one yourself from scratch like these

Geez Rabbi I thought you were more knowledgeable on mobile CB antennas. There is plenty of center load mobile antennas out there that can be used for cars or trucks!

The Predator 10 K first comes to mind like the one pictured below., Monkey made, K-40 SS steel coil, and even those steel coil truck stop cheapies are center loaded.

 

[rabbiporkchop]

Geez Rabbi I thought you were more knowledgeable on mobile CB antennas. There is plenty of center load mobile antennas out there that can be used for cars or trucks!

The Predator 10 K first comes to mind like the one pictured below., Monkey made, K-40 SS steel coil, and even those steel coil truck stop cheapies are center loaded.

For it to be considered a center load the Whip and the shaft should be identical lengths.
I don't see that very often. 99% of the time the shaft is shorter than the whip itself making it a bottom load because the load is below the halfway point.
Unfortunately none of those antennas have a tunable coil and are a predetermined length. You are correct they can be used in any situation but they will never be ideal for every situation. The ideal antenna would be as long as possible but with a tractor trailer that's generally not going to happen so to make it as long as possible would require a custom coil tuned to match a specific length to fit within a specific space on a specific vehicle. Sure I could put a gunny Puck on the roof of my Tahoe and put a heavy antenna on top of it and smash into a tree branch and rip a hole in my roof but why would I want to do such a thing when I can make such a small compromise and put a bottom load on and enjoy the benefits of having a huge sheet metal roof?
You can put the world's greatest antenna on a tractor trailer and it will still not ever come close to the performance I can get out of a bottom load antenna on top of a giant sheet metal roof. One nice thing about my antennas is that I can make them any length I want and simply tune the coil to match the physical length. This coil Winder sure comes in handy for making uniform spacing.

 

[rabbiporkchop]

If I had a Kenworth T600 with an antenna mounting location 81 inches off the ground that would give me 81 inches of room to put an antenna without going over my height restriction and unfortunately none of those manufacturers make an 81 inch antenna so I had to build one for myself and tune the coil to match the Physical length. In a perfect world, The antenna should be as long as possible and the coil should be as short as possible which means that every antenna should be custom built for the specific Vehicle and the height restrictions. Nobody wants to pay that kind of money that's why we have monkey made and Predator 10-K antennas available to the public

 

[fourstringburn]

The ideal antenna would be as long as possible but with a tractor trailer that's generally not going to happen so to make it as long as possible would require a custom coil tuned to match a specific length to fit within a specific space on a specific vehicle.

Do you admit you were wrong that there is center loaded mobile antennas? Sounds like it in a skirt around way.

Depending on the model, the predator Antenna is long, it's over 80 inches. These are CB antennas so the coil is already within tolerance of where it needs to be for the tuning range of the antenna.

These work fine for Trucks and many people run them. You don't need a custom coil. If you want an adjustable coil then get or make a screwdriver but that's not practical or money smart if all you do is run on the CB band. If you cut back on the coil, then you will have to lengthen the whip or vice-versa . Since these antennas are about 20 inches short of a 1/4 wave whip, nothing substantial will be gained so why bother screwing with the coil.

You can put the world's greatest antenna on a tractor trailer and it will still not ever come close to the performance I can get out of a bottom load antenna on top of a giant sheet metal roof

You are always talking in absolutes that's why you get caught wrong often!

Not true in all cases.

Yes if you pull vans and reefers with mirrors mounts,

Absolutely Not if you pull flatbeds, tankers, and car haulers and you have a true flatop truck with the antenna mounted up high behind the cab dead center of the vehicle. Tanks and car haulers are best and have over 50 ft. of extra metal over your Tahoe.

Got you dead to right this time!!! Stop trying to outsmart everybody like your buddy Mark!

 

[rabbiporkchop]

I'm not out trying to outsmart anybody I'm simply stating that nobody makes an antenna worthy of my liking so I have to make my own.
this only applies to tractor trailers. There's lots of nice roof mount antennas for cars that Make it pointless for me to make an antenna for my vehicle since there are so many to choose from that work quite well on my Chevy Tahoe without putting strain on the thin sheet metal roof. When it comes to tractor trailers though I'm very picky about the antennas that I use and those antennas must be accurate within a quarter inch of a specific measurement that I decide and nobody will sell me what I'm looking for so I have to make my own. Everybody's free to purchase antennas where they want to but nobody is willing to make me an antenna to my specifications cheaper than I can make it for myself so I end up building them for myself.

 

[rabbiporkchop]

This right here looks like the most bang for the buck and it probably cost about $26 at a truck-stop plus the cost of the stainless steel shaft extension. Looks like a smart budget-conscious driver drives that truck.

 

[fourstringburn]

I did the same thing with a Sirio 5000