Ah, the dual CB antenna installation! Few things compare in terms of the looks, bravado and downright classic rugged feel it gives to a pickup truck or big rig.
But for pickup trucks especially, dual antenna installs are often chosen for the wrong reasons or with unrealistic range expectations. In this guide, we'll walk you through everything you need to know regarding a two antenna installation.
Benefits of Dual Antennas
There are a number of different reason you might consider installing dual antennas onto your rig:
Prevent Signal Blockage
If you're pulling a large trailer, camper or 5th wheel, there's a good chance that it will block your antenna from transmitting in certain areas.For example, say your antenna is mounted on the front right side of your truck. When towing a large 5th wheel, the antenna won't be able to transmit or receive well to or from the rear left side of your vehicle. The 5th wheel will likely be blocking it unless you're using an extremely long antenna.
That's when having two antennas comes in handy. With antennas on both sides of your vehicle, you're much less likely to have large dead spots because the antenna system can "see" more.
This is one of the primary reasons most 18 wheelers have dual antenna setups. Without them, the large trailer being pulled would create large dead spots.
Increase Range Up and Down the Road
You've likely heard that dual antennas will increase your transmit and receive range, and this is partially true as long as you're talking to people either directly in front of or beyond your vehicle.
Assuming no obstructions, a single CB antenna has a uniform, circular signal pattern. It can send and receive in all directions equally, as illustrated by the picture below.
Dual antenna installations don't have the same signal pattern. Instead of being perfectly circular, their pattern is much more oval shaped - with the oval being stretched in the direction of travel.
So with a dual CB antenna setup, you'll be able to talk further up and down the direction of travel, which usually works out well given the direction of most roads. Yet, you do lose a bit of range to the right and left side, which isn't ideal for all circumstances / drivers.
Requirements for Dual CB Installs
When installing a dual CB setup, you need an absolute minimum of 5' between the two antennas. Anything closer, and the antennas will be too close to perform properly. Ideally, you should be closer to 9' as a minimum for peak performance.
In addition to two antennas and mounts, you'll also need a special co-phase CB coax for wiring everything up. Many people will attempt to use standard CB coax and a "T" adapter to connect the two separate antenna coax and the radio, but this WILL NOT work.
Instead, make sure you get a special co-phased, RG-59 CB coax cable. This is a special "Y" cable that has two ends going to each antenna, which come together into one end which plugs into your radio.
Again, without this special cable your dual antenna setup simply won't work.
Keep Those Antennas Long!
Finally, just because you're using two antennas doesn't mean you can scrimp on length. A good 5-foot single magnet mount antenna installed high on a pickup's roof will outperform a smaller 2-foot dual antenna setup.
While you'll get the increased range up and down the direction of travel, you'll still need decently long (and properly installed) antennas to enjoy great performance. So make sure to pick as long an antenna as you can comfortably mount and enjoy the best of both worlds.
Dual Antenna Recommendations
Our favorite dual antenna kit is from Firestik, and includes everything you'll need to get a high-quality dual setup installed. You can lean more about the dual Firestik CB antenna kit here.
If you're looking for just a cable, we'd recommend this dual CB coax cable with removable PL-259 ends. If you need a lower profile cable, go for the Firestik CB Coax with Terminal Ends.