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transmitter and receiver sharing antenna

Discussion in 'Electronic Basics' started by JTM, Jun 19, 2004.

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  1. JTM

    JTM Guest

    I want to use a Radiotronix 433 MHz transmitter and reciever together (so I
    can TX and RX from the same device) and want to know if there is a way I can
    use the same antenna for both.
  2. the Wiz

    the Wiz Guest

    Yes. For a low power transmitter, you can use the proper switching/isolation
    diodes to connect the antenna to the receiver until the transmitter is turned

    For higher power, you can use an RF-rated relay to switch the antenna between
    the transmitter and receiver.


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  3. Captain

    Captain Guest

    It depends on the bandwidth ofthe antenna and whether or not you want to
    operate in simplexx or duplex mode.

    Simplex is simple, all you do is use a relay or diodes to switch between
    transmitter and receiver and you can use the same frequency for both
    transmit and receive. You cannot, of course, receive while you are

    Duplex, that is, the ability to transmit and receive simultaneously, on the
    other hand, requires different frequencies for transmit and receive and
    usually an isolator circuit between the tx and rx parts of your radio. An
    accurate, high power, notch pass filter, tuned to the receive frequency is
    also useful. The frequencies should be far enough apart that the transmit
    signal can be filtered successfully from the receive signal, hence the
    bandwidth of the antenna becomes critical.

    If you need to use duplex operation then you need to do a bit of studying,
    designing and building. Simplex operation is well named!


  4. JTM

    JTM Guest

    I'm thinking it might be better to just power down the RX and power-up the
    TX as needed.

    I found some ascii-art on the web on the use of diodes to share an antenna,
    but can't seem to find it again. The schematic was simple but they
    mentioned the diode selection was critical. Can someone provide the details?
  5. Jamie

    Jamie Guest

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