preps
Results 1 to 6 of 6

Thread: Is there any advantage to running 2 antennas on a tractor trailor vs 1 antenna??????

  1. #1
    Join Date
    Apr 2013
    Location
    loess hills,USA
    Posts
    2
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Downloads
    0
    Uploads
    0

    Is there any advantage to running 2 antennas on a tractor trailor vs 1 antenna??????

    I'm thinking of going back to 2 antennas on my Peterbilt. Has anyone seen any advantage running 2 vs 1 antenna even with power??

    Thanks

  2. #2
    Join Date
    Oct 2012
    Location
    Missouri City, Texas
    Posts
    4
    Thanks
    0
    Thanked 2 Times in 2 Posts
    Downloads
    0
    Uploads
    0
    Running with two antennas on a tractor trailor helps to even out the transmit pattern as transmission patterns tend to pull more to were the body mass is. Mount the antenna on the left the transmission pattern will be greater to the right, the same will happen if it is mounted on the right the pattern will be greater to the left. When two are used they give a more even transmit pattern to the front and back. If using power with a cophased antenna system keep in mind that the coax used in most kits will only hold about 1500watts P E P.

  3. The Following User Says Thank You to onesixdoublezero For This Useful Post:

    High Voltage Mobile NJ (05-03-2013)

  4. #3
    Join Date
    May 2013
    Location
    Georgia
    Posts
    53
    Thanks
    5
    Thanked 26 Times in 17 Posts
    Downloads
    0
    Uploads
    0
    Another thing to remember when adding a co-phased end fed mono-pole antenna system is ensure you use a equal amounts of 75ohm coax and try to keep the distance of the antennas close to 1/4 wave length part to keep your radiation patterns symmetrical...EZNEC is a great antenna design program to mess around with and it show you everything you would like to know about your antenna set up and design flaws. 75 ohms coax is used because the impeadance increases from approx 36 ohms of a standard 1/4 wave design to nearly 75ohms with a dual phased system...ensure you join to a good 50ohm T and run back to the radio with good 50 ohm coax. 8 ft seperation may not be possible but try to get the most separation you can...reason truckers place on mirrors instead of roof, that and it easier too...
    Last edited by Moonchild 747; 05-04-2013 at 08:18 AM.

  5. #4
    Join Date
    Aug 2012
    Location
    Round Rock, TX
    Posts
    394
    Thanks
    94
    Thanked 196 Times in 100 Posts
    Downloads
    7
    Uploads
    0
    Silverado 996 back in the woods and I'm gone!
    * Cobra 29LXLE *
    * Ranger 2970N2 * 5' FireStik FS-5 *
    * Uniden BearCat 12 watt spearker *


    "It is not the strongest of the species that survives, nor the most intelligent, it is the one most adaptable to change, that survives"

    - Charles Darwin

  6. #5
    Join Date
    May 2013
    Location
    new york city
    Posts
    6
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Downloads
    0
    Uploads
    0
    The advantage will not be noticeable if any. Antennas are too close together. 2 antennas 2 headaches. Co phase antennas work better when a certain feet apart. A truck is not wide enough. I tried this many years ago and notice no advantage in my van.

  7. #6
    Join Date
    May 2013
    Location
    Georgia
    Posts
    53
    Thanks
    5
    Thanked 26 Times in 17 Posts
    Downloads
    0
    Uploads
    0
    Quote Originally Posted by peterwo2e View Post
    The advantage will not be noticeable if any. Antennas are too close together. 2 antennas 2 headaches. Co phase antennas work better when a certain feet apart. A truck is not wide enough. I tried this many years ago and notice no advantage in my van.
    Exactly...Dual antennas should be 1/4 wave length apart to achieve the right 50 ohm match at the radio and intended directional RF pattern...But you'll see them on trucks anyway and they because putting one up on the side of your truck will pull the signal toward the opposite side of the truck...Placing two on opposite sides but closer that 1/4 wave length or 8 ft will just give you more balance with your signal, much like placing the antenna in the middle of the roof giving you omni direction.
    de 747 and I'm clear...

    "He who controls the electromagnetic spectrum controls the world..."

  8. The Following User Says Thank You to Moonchild 747 For This Useful Post:

    the caveman (07-23-2013)

Visitors found this page by searching for

what type of antenna is used with the cobra 29 lx cb tractor

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •