not necessarily true. any metal in the line-of-sight to the antenna will affect the signal propagation from the antenna. also, mounting the antenna at the front of the bed, on the rail, will be more directional towards the rear of the vehicle than towards the front since the bed will act as a ground plane. not that it won't work acceptably, but will have directionality and better sensitivity towards / from the rear.

 

So you think I should keep the 108in whip, mount it in the center of the bed, with a spring with a nylon bushing inbetween the spring and base, and the mount and bed?

Okay the grounding part of this is confusing me... I am pretty sure thats why my CB burned up...where exactly should I ground it, you are saying on the coax, but I dont understand how to do that??

 

The coax has two conductors- a center conductor and a shielding conductor. The center conductor goes to the antenna and the shielding conductor is the ground.

 

And in general, mounting the antenna to the rear bumper won't make a huge difference in performance, particularly if you're using a basic CB without external amplifiers, etc., so if you want to put it there, go ahead.

I tend to get a little technical and trend towards "best case" since I work in the wireless industry, dealing with antennae and such. But that doesn't mean you won't get satisfactory performance mounting it elsewhere.

 

If you have a truck stop close by go in the c-store and get a L bracket mount and a L bracket mount stud it will be all you need to mount it to the bed rail.

the L mount will have a hole for the stud on the bracket you can feed the stud with the plastic isolators (one on top one on bottom of hole in mount)just like they come in the package with the bolt of the stud on the top side of the mount so the treads go downward then screw the base of the spring to the bolt and the coaxl to the bottom side.

Found a picture of what I am talking about for you

 

Yup. That's one way to mount the antenna.
Hopefully, seeing the pic makes sense. The mount should take care of grounding the system for you.

 

Wow this is why I love yotatech.

See nobody ever told me where or how to mount the antenna so I put it where it looked the best in my own opinion, and that was that.

I was never really able to talk to any body over a .5 of a mile like you said and could never figure it out.
Thank you so much for this info

One of the best threads here latley to full of very use full information.

keep up the good work

 

Oh I agree that it looks good there. Just don't work too good. If you want to leave it there since you already have a hole drilled there then visit a truck stop & find the tallest top loaded antenna that you can mount onto your truck. In case the package doesn't say "top load" just look at the coil. Yours is on the bottom. Find one that has the windings on the top & it should help you out a bit. Make sure to set your SWR's too. If your CB doesn't have a built in SWR meter then you can pick one up at the truck stop or maybe radio shack for around $25-$35 bucks or so. If you are into CB's it will pay for itself. You will either adjust it by loosening the set screw and moving the tip -or- the copper winding itself (depends on the antenna) I would get an adjustable tip if you can. Keep adjusting it until you get the SWR's as low as possible & you are good to go. Make sure your engine is off, doors are shut & you are in an open area when adjusting it. Good luck to you.

 

The bumper is not necessarily a bad place to mount the antenna. You will find that the sides of the truck block the signal. So since your antenna is at the left rear corner, you'll have a hard time getting any distance across the truck, towards the front right. Many problems with signal propagation from CB's are due to not properly tuning the antenna or coax installation issues such as the coax getting pinched going through a door jamb, chaffed or broken outer shielding caused by sharp edges, etc.

For most people, the discussion of base vs. center vs. top loaded antennas is merely a personal choice. Most fiberglass whips are top loaded for a reason- so you can clip the top of the antenna to tune it: they are pre-tuned at the factory but the addition of the mount, springs, etc increase the effective radiator length of the antenna so the antenna itself needs shortened to compensate. Metal mast antennas are usually bottom or center loaded and have set screws so the effective antenna length can be adjusted for tuning. Some people will also tune their antenna for optimal Voltage Standing Wave Ratio (VSWR) on their preferred channel / frequency. Others who talk on multiple channels will tend to tune it to the center of the band (frequency range) expecting some loss of performance at the highest and lowest frequencies (channels). And some may have antenna matching hardware that physically alters the characteristics of the coax to provide a better match between the radio and antenna, but these tend to not enhance performance as much as physically tuning the antenna.

Not properly tuning the antenna results in radio waves being reflected back towards the transmitter. These reflected waves reduce the strength of the signal radiated from the antenna and increase the load on the amplifier circuitry in the transmitter. A perfect VSWR match of 1:1 is impossible under most conditions since connectors, changes in coaxial cross-section due to bends in the cable (like how bending exhaust pipe changes the shape of the pipe at the bend) and the resistance of the cable and antenna cause reflections towards the transmitter and even putting a VSWR meter in line creates reflections. 1.1:1 is usually as close as one can get in practice, 1.3:1 is more normal and anything higher than 1.5:1 should be avoided.

People often cite a minimum length of cable required between the transmitter and antenna as well to help the efficiency but in practice that is not true. The shortest amount of cable necessary to make the connection is all you need. Unless you're dealing with certain types of antennas with multiple radiators such as directional, or beam, antenna or are co-phasing antenna (using two antenna for a better radiation pattern) and thus require the antenna to radiate the signals in such a way that they do not interfere or cancel each other due to differing phasing, cable length is not a concern.

The amount of power output is not a huge concern either. Given proper conditions- antenna type & location, tuning, etc, it's possible to talk around the world on 4 watts. More than 4 watts, though illegal, is possible as long as the coax is properly rated for it and the antenna can effectively radiate it. If the antenna cannot radiate it, radio waves are reflected back towards the radio and can damage the equipment. High power becomes an issue because the antenna will become warm, the heat changes the resistance of the antenna and consequently the impedence presented to the radio. This in turn causes the VSWR to change.

turborich's mention of a 108" whip antenna being best (which I could argue since yagi's can have gain in excess of 12dB, making them transmit farther and receive better than a whip, but they aren't practical on a vehicle since they are highly directional) due to the fact that it is physically very close to 1/4 wavelength of the CB frequencies (108"*4= 432" = ~11 meters). Physically shorter antennae will have either a coil (base or center load) of wire wound close together so the effective length is 108", some fiberglass antennae such as Firestik have the wire wrapped around a fiberglass rod where the wraps get closer together towards the top, to the point of the coils of wire are next to each other, making it easy to cut off a mm or however much is necessary to tune it and others may have a screw in the top to adjust the overall effective length of the antenna. And we're only talking 1/4 wave antennae here. There are also 3/8, 1/2, 5/8, 3/4, 7/8 and full-wave antennae available, both directional and omnidirectional, in configurations from whips to dipoles, yagi's, beam, etc... but they are not practical on a vehicle either mainly due to their cost and / or size.

 

I will stick to my original comment that the 102" whip is the ideal antenna but like I said, the length makes it undesirable. All of the guys with "BIG RADIOS" around here either run 108" stainless steel whip or a Wilson 5000.

Why on earth would you compare a Yagi to a whip? That doesn't make sense as it's directional just as you yourself said. I wouldn't put a whip on my vehicle unless it was an old beater just because it would look crazy & hit everything around. I would go with a Wilson 1000 & call it done as long as you didn't mind drilling a hole through your roof. I am NOT a big fan of mag mounts.

Base loaded vs middle & top loaded isn't a personal choice when you have it mounted on a bumper behind a tailgate or behind a cab, etc. Then you need a top loaded antenna so that you can at least try to get your SWR's somewhat low. If it was mounted on your roof then yes I would agree that it would be preference. Go ahead & mount a base loaded antenna on the side of your truck & check the SWR's. You will never get them down low enough.

These other antennas that you bring up are for base stations that do not move around & shouldn't even come up in a conversation about a mobile CB set-up. I was trying to help some folks out, not confuse them.


Here you go, read this as it's very simple.

http://www.wearecb.com/products/antenna/cb_antennas.htm

 

I suppose we each have our own opinions.
But I deal with coax, waveguide, antennae, VSWR..., "return loss", "insertion loss", propagation velocity, and such all the time. Comes with the job- building radio, microwave and cell towers for a living.

I'll leave it at that.

 

If you're using the CB only while you offroad then you really don't need to peak/tune/point/play/giggle/fart/etc and I'm pretty sure it doesn't matter if the antenna is on the top/side/front/rear/underneath/etc.

If you're using it for communication in a "line of sight" of less than 100 yards (like most off road trips) then I think you'll be fine as long as everything is grounded and hooked up properly. I used a little Uniden 520 and a hard mount Willson Lil' Will 1000 and never tuned a damn thing. It worked perfect for what I needed.

Lets not get too wrapped around the antenna on this one.