This is due to the fact that an antenna is radiating radio-frequency signals of a specific wavelength. A properly tuned antenna will have a length that will accurately match the radio frequencies wavelength it is transmitting. A full wavelength antenna would be slightly longer than For mobile purposes, the height of a full wavelength antenna would be impractical. So it is common practice to use antennas that are a fraction of the full wavelength.
For mobile CB antennas the quarter wave antenna is just under 10 feet long and take to form of the common whip antenna. Each channel is on a different frequency, thus requiring a different antenna length to exactly match each frequency.
The antenna and antenna feed line have what is called characteristic impedance, or a measure of resistance to the current flow through the wire and out the antenna. When a transmitter is connected to an antenna by a feed line, the impedance of the antenna and feed line must match exactly for maximum energy transfer from the feed line to the antenna to be possible.
In the less than ideal scenario, a portion of the electrical energy from the CB is not converted into radio wave energy and instead is reflected back down the feed line and into the CB radio. For a good and less expensive solution, look at the Little Wil antennas. The Little Wil is the smallest magnetic antenna from Wilson, and it out performs all similar types of small base loaded antennas.
It was designed specifically for users who want a high performance antenna with a short whip at a low price. Both of these are very flexible, have various lengths to choose from, and offer easy tune options.
Mounting location is important for the effectiveness of your antenna. The general rule is that the higher the antenna is mounted, the better. Also, you want it vertical.
At a minimum, the coil and most of the antenna needs to clear the roof line of the vehicle to avoid interference and having too much of the signal reflected back into the antenna. All other things being equal, the higher that your antenna is above the roof line, the better your reception and transmission.
You also don't want the antenna mounted where it will break off easily. You can mount the antenna on the fender, but if you mount it on the front driver's side, the signal will be weaker to the front-left of the vehicle. An essential part of the overall electrical length of the antenna is the coax cable.
You will need to consider how long the coax needs to be to run from the radio to the antenna mount. If you mount the antenna in the back of the vehicle or the mirrors of a semi, you'll need more coax cable. We always recommend that you get 18 feet of coax even if you don't need that much to attach the radio to the antenna mount. Most CB antennas are somewhat pre-tuned with 18 feet of coax. If you select coax that is shorter or longer than the 18 feet, you might come across some issues with achieving optimal SWR readings.
If you must go shorter or longer, try to s tay in 3 foot increments to match the wavelength of the radio. If you have extra cable, don't cut it off or coil and wrap it. When you coil the excess coax, it is essentially creating another antenna coil and could severely effect SWR readings.
Instead, be sure to properly store any excess coax in a figure 8, about one foot in length, and bound in the middle. It should look like a long, skinny 8. If your path has to run through the firewall, a window or interior linings, you'll have to consider the size of the connectors on the cable. It may be better to get cable with detachable connectors.
There is a difference between the ground plane and an electrical ground. Your antenna needs both. The mount your antenna is connected to needs to have a good ground to the vehicle chassis. For metal mounts, this is achieved through metal to metal contact.
You can test this with a light, just as you would test any vehicle ground. If you don't have a good ground, you could scrape paint off where the mount contacts the vehicle, but many people don't want to do that.
A good alternative is to use a grounding strap from the mount to the chassis, but the grounding strap needs to be as short as possible. For magnet mounts, the ground is formed when the magnet couples with the metal of the vehicle. Good quality magnetic mount antennas shouldn't have a problem with grounding. NGP antenna systems do not require that the antenna mount is electrically grounded. This is VERY important! Tuning your CB antenna not only optimizes the performance of your antenna system but also helps to reduce the potential to damage your radio by operating with high SWR readings.
We have several articles in our Help Center to help you. Check them out! CB radios operate on channels , and one antenna cannot provide ideally tuned reception for all of those. Most people opt for the middle ground and tune the antenna for best reception at the mid-point. SWR meters will also help with trouble-shooting your equipment to find a bad coax, a poorly grounded mount, or a weak or non-functioning ground plane.
Not only does it provide ease of tuning, it broadens the antenna's bandwidth to keep the SWR lower over more channels. To tune an "FS" antenna, you just remove the tip and turn the adjustment screw up or down as needed. Always tune the antenna when it's in the final location.
You also need to tune the antenna every time you move it, add a spring or quick disconnect, and every time you modify your vehicle with a large metal component. We recommend that you check your SWR readings as part of regular system maintenance to ensure that it is always optimized. Choosing the best CB Antenna for your needs starts with education. Knowing what to look for, in relation to your specific setup, is the first step in ensuring that you buy the best CB antenna for your unique situation.
We're here to help, so please don't hesitate to contact us or feel free to browse our CB antennas for sale now that you know what to look for! About Us. Store Links. Customer Service. Get advice, hear about specials, and much more when you follow us on social media!
Read more From all of us here at CB World, we wish you the very best. Search CB World. Do you have questions? We have lots more on the site to show you. You've only seen one page, click here to see our most popular article ever! When it comes to dual CB antennas, there is quite a bit of misinformation out there. Some swear by dual CB antennas and claim they are better than singles in every way, but is that true? There are numerous reasons you might want to consider installing dual antennas.
But the real story is much more complicated than that. Of the claims made about dual antennas, the two most popular are that they give you a longer range and their signal is never interrupted.
This one is half true and half not.
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