RF interference and extending a transmitter antennae

Discussion in 'Wireless & RF Design' started by Jsabah, Oct 31, 2015.

  1. Jsabah

    Thread Starter New Member

    Oct 31, 2015
    4
    0
    I am new to the electronics arena so please bear with me... A bit of project history.... I am restoring an old car and want to change the steering column to a rack and pinion. The current column allows for the wires of the turn signals and horn to go down the center into the engine bay and connect to the respective systems. Problem is with the new steering column no wires can run down the center and the turn signals and horn switches are located in the center of the steering wheel.

    My solution (other than relocating the switches to the dashboard), which I have done is as follows: I purchased an inexpensive 4 channel tx/Rx set. Opened up the transmitter and de soldered 3 of the switches and replaced with wires that connect to the existing turn signal and horn switches. The transmitter is to be left in the steering wheel hub. On the receiver end it has been programmed to stay on as long as the "button" is pushed and via an automotive relay turn on and either the turn signals or horn.

    Now for the problem... The steering wheel hub is made of metal and doesn't allow the signal out. My idea of a solution is to use an extended antenna and bring it to the front of the steering wheel, which is plastic/Bakelite. If I need to relocate the receiver for better reception, that can be done but 1st I need to get the signal out of the steering wheel. The tx antenna is currently a pull out metal type and I have read that the length of the antennae is based upon the frequency. I tried straighten in the receiving antennae but that just seemed to make the system work intermittently even when on the bench (nothing in the car). Any help would be greatly appreciated.
     
  2. Jsabah

    Thread Starter New Member

    Oct 31, 2015
    4
    0
    Any help here?
     
  3. PRFGADGET

    Active Member

    Aug 8, 2011
    51
    7
    You might try a length of RG-174 coax from the transmitter to a point near the receiver antenna.
    Terminate the coax in a length of insulated wire the same length as the telescopic antenna you disconnected from the transmitter.
    Alternately you could try the reverse with the receive antenna .
     
  4. Jsabah

    Thread Starter New Member

    Oct 31, 2015
    4
    0
    This worked out great! Thank you. Follow up question.... Can I use 2 transmitters simultaneously if they are both connected to a single 1/4 wave antenna via two RG-174 cables? I ask because I currently have a 4 button transmitter with 3 of the buttons connected to the turn signals and horn (right,left, horn) and find that I can't operate the horn while the blinker is in operation/transmitting...a solution would be to use 2 seperate transmitters but I only have room for 1 antenna hidden in the hub under the horn button. Thanks again!
     
  5. PRFGADGET

    Active Member

    Aug 8, 2011
    51
    7
    Two transmitters on one feed line do not play well together (normally).
    Since you are dealing with very low power, you might try a coupling capacitor at each transmitter to the rg-174 or an L-C circuit designed for each transmitter .
    The simplest thing to do would be to just run a second length of RG-174 from the second transmitter.
     
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