Ok some might think this is a dumb question but here it goes. What is the best shortest mobile CB antenna? I know that the longer the better range and stuff but what do you think the most efficient shortest antenna is?
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Best shortest mobile CB antenna??
- Thread starter Galaxy 959
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A short, efficient antenna is an oxymoron.
You know; sorta like like freeze dried water.
Ain't gonna happen . . .
Anything less than a 1/4 wave length is less than unity gain. So they are all a compromise. The shorter they are; the more compromised they are. Five feet or less is a waste of both time and money; especially money . . . don't buy into that BS that says 'it is a 5/8 wave' - nooooo way . . .
You know; sorta like like freeze dried water.
Ain't gonna happen . . .
Anything less than a 1/4 wave length is less than unity gain. So they are all a compromise. The shorter they are; the more compromised they are. Five feet or less is a waste of both time and money; especially money . . . don't buy into that BS that says 'it is a 5/8 wave' - nooooo way . . .
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That depends on a lot of factors. How much range do you need? Do you want a fixed mount or a magnetic? How much portability do you need?
I've got a bunch old Radio Shack magnet mounts with a 32" stinger that work great for most of what I do. I've also got a Stryker 5K and a Wilson 1000 - both with 62" stingers. They get out a little better. Then I've got the trusty 102" whips for the big chores.
Those little 10" jobs I wouldn't recommend for anything.
I've got a bunch old Radio Shack magnet mounts with a 32" stinger that work great for most of what I do. I've also got a Stryker 5K and a Wilson 1000 - both with 62" stingers. They get out a little better. Then I've got the trusty 102" whips for the big chores.
Those little 10" jobs I wouldn't recommend for anything.
I have a Sirio Performer 5000 now that is about the best I can get. But the problem is its just way to long. I knocked it completely off the top of the truck the other day going to work. Was just looking for something decent with maybe 10 mile range or so for local. It has a 80" whip I think. I know its over 12' to the tip from the ground.
I don't like anything for mobile use other than a steel whip, or a fiberglas whip (like the old Francis Amazer). But ... if you need a something shorter than the 5000, I would recommend a top loaded antenna such as the PAL Firestick or the like. I ran a 5' Firestick for years, and had good results. Handles power pretty well too. 73s.
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Gotta agree with all the above. Height is might. How are you running the antenna as a mag mount I suppose? And what magnet are you using? Hopefully the PL145 mag mount by Sirio and not something like a Wilson 5000 mag mount as they wont hold the performer 5000 up as well as the Sirio PL145 mag mount will. You didn't mention this in the post. Just curious. I ran a Sirio performer 5000 on top of a work van that was almost 9ft tall and I used the Sirio mag mount. It never came off and I hit a lot of stuff with it. How low of stuff are you hitting? On a regular vehicle or even a regular truck you should not be hitting too much stuff I wouldn't think unless you're out in the sticks and the trees hang low. But like said, try to stay as tall as possible as the shorter you go the worse the performance will become. JMHO. Hope you get it resolved.
Using the Sirio pl145 magnet. Hitting limbs going out my paved road. About 3 miles worth. It's over 12' tall on my truck. The antenna is tough you hit 1 low enough it don't give.
Okay. I totally understand now. Yeah that is pretty low of a hit I'm sure if it knocked it off. If it would have hit higher up it most likely wouldn't have come off. Mine would take a low hit but I also had 6 magnets on the underside of the roof. The main one directly under the antenna being a PL145 with the coax cut. It held its ground through some darn rough hits. Never came off with the stock whip. And that was with the older style 4mm vs. 3.5mm whips. Don't seem like much, but the older antennas were a bit beefier. At any rate you have some homework to do. Most likey something either mounted in the bed of the truck, or on one of the bed stake holes. What you are speaking of in your last post might work. Might be more directional, but if it will work go with it. You could also try a center loaded Sirio performer 5k trucker antenna in one of the bed stakes. Just get the coil to the top of the roof of possible. Wilson I think makes replacement bottom shafts in different lengths or check around on google for some of the antenna builders, they may have something that will work for you as well as having bottom shafts. Hope you get it figured out. Be safe and good day.
Agreed short antennas are a waste unless you live in a area where you have to deal with low hanging tree limbs, or you don't want to draw attention to your vehicle. Antennas can "Electrically 5/8 in wavelength" and not be any where close to that in physical size. I don't believe you will get the receive gain from the "Electrical 5/8 wave" but phase shifting using capacitors and inductors would make it seem like a 5/8.
The best short antennas I have used are like "FireStik" designs. I have seven antennas that are labeled "Ham Stiks" from MTC in Texas as well as firesticks for 11 meter. I know a lot of people dislike FireSticks, but I have had good luck with them.
There is no way, no how to mount a mobile 1/4 wave antenna for 75, 40 and 20 etc. meters. But for 10, 11, and 6 meters on up you can easily.
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Agree about the steel whip.
once the load gets higher than 1/2 way up the antenna, the antenna gets less efficient due to increased Q loss.
what many people refer to as a top loading coil is really a capacitance hat which will increase radiation resistance.
I think to try and apply a blanket statement is going to be hard. What might be good for my best short antenna may not be yours.
That being said, I have had some good success from Wilson Silver load 4' where the mounting is on a 3/8-24 type mount. For mag mounts, Wilson 1000. Not the power handling of the 5000 or Sirio's but I have found that the magnet stays put.
The so called mobile CB 5/8 wavelength antennas are not actually electrical 5/8 wavelength antennas. An electrical 5/8 wavelength will have a very high X (reactance) at the feed point just like the full length 5/8 wavelength antennas. Because of this they would require additional matching just like the full length 5/8 wavelength base antennas which they do not have.
A top loading coil is not a capacitance hat, and works very different than a capacitance hat. As a matter of fact, how the two different devices work is exactly the opposite of each other. A coil, which is an inductive load, no matter where it is on an antenna including the top, will lower the feed point impedance, and thus radiation resistance, at resonance. A capacity hat, which is capacitive load, will raise the feed point impedance, and thus radiation resistance, at resonance. There are antenna designs that use both a capacity hat and a top load immediately below it as a means to always getting that so called "perfect" SWR...
The DB
You beat me too it. I would also like to add that the higher the load is the MORE efficient the antenna becomes not less. This is because of lower RF current and less losses in the coil. You can however use a smaller coil at the base but it should consist of much larger wire.
Gee, I dunno 'bout that... once a loading coils is placed ABOVE about 1/2 way up a mobile antenna, the efficiency does decrease.
relocating the loading coil to the approximate center of the antenna, the current node will rise.. This fact doubles the radiation resistance. to this point, the efficiency has increased, however,..., but there is a bit more coil (Q) losses as center loading approximately doubles the required reactance for resonance.
locating the coil higher up (higher than center),will increase Q losses that will more than offset the increase in radiation resistance.
The resonant loading reactance varies inversely with the antenna length. the Efficiency varies slowly with load point and peaks at roughly 0.4 of the whip length.
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