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  1. #1
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    Place TX/RX Antenna?

    Hello

    I need help for TX and RX antenna in TRX system.
    How to place antenna in uhf band?
    How much isolation between TX and RX antenna?
    Is the TX antenna influence in RX or not?

    best regards

  2. #2
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    Re: Place TX/RX Antenna?

    What do you specifically mean with "TRX system"?

    Why not elaborate the question? What do you try to achieve, why do you require isolation between RX and TX antenna? Do you intend half or full duplex operation?



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  3. #3
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    Re: Place TX/RX Antenna?

    i have a full duplex system and i think the TX coupling on RX antenna. because the RX going to saturation( I think.)

    Now how can i fix it?

    thanks and regards



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    Re: Place TX/RX Antenna?

    Go and measure the coupling, instead of guessing.



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    Re: Place TX/RX Antenna?

    Ok, But how to measure it?

    - - - Updated - - -

    Hello

    Look that noise floor when the PA is on and so off.
    When PA is turn on, the noise floor more than 10dB than the PA is off.

    https://pasteboard.co/J1sQWgU.png

    how could i fix it?

    regards.



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  6. #6
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    Re: Place TX/RX Antenna?

    Quote Originally Posted by mehdu View Post
    Ok, But how to measure it?
    Network analyzer S21 measured from TX antenna to RX antenna

    Quote Originally Posted by mehdu View Post
    how could i fix it?
    More distance between the antennas, possible anechoic absorbing material to reduce leakage, reduce near field reflections ... it really depends on your setup and other antenna requirements.


    1 members found this post helpful.

  7. #7
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    Re: Place TX/RX Antenna?

    Hello Volker,

    i couldn't measure S21 from TX ANT to RX ANT.

    But when distance between the antennas as more as possible, it's better.

    regards.



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    Re: Place TX/RX Antenna?

    Quote Originally Posted by mehdu View Post
    i couldn't measure S21 from TX ANT to RX ANT.
    What is the reason? You need to know, so that you can verify possible modifications.



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    Re: Place TX/RX Antenna?

    Because i don't know how to measure it.
    If possible help me more. ( with block diagram and description)

    thanks.



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  10. #10
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    Re: Place TX/RX Antenna?

    Quote Originally Posted by mehdu View Post
    Because i don't know how to measure it.
    If possible help me more. ( with block diagram and description)

    thanks.
    I don't want to sound rude; but as the one who wants help; you need to give us a better description of your situation; so we can help you without giving you misinformation.

    1- if possible show us a picture of your setup
    2- is Tx and Rx antenna in same PCB, or are they on different planes i.e (distance between them) ?
    3- What is the Frequency, Bandwidth (narrow or wideband antennas) and antenna type etc.?



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    Re: Place TX/RX Antenna?

    1- I can't take a picture. The antenna (RX and TX) installed on tower and have 5m distance between them and the cable length is about 20m and then connect to Device.
    2- Yes, Both of them in same PCB.
    3- UHF band with narrow bandwidth. and antenna type is omni like as "Laird Technologies FRX450 450-470 MHz 5dBi Fiberglass Omni Antenna"



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    Re: Place TX/RX Antenna?

    Quote Originally Posted by mehdu View Post
    antenna type is omni
    Then perhaps a vertical offset helps, because the antenna radiation is smallest there.

    If you have different TX and RX frequencies, you will need a diplexer
    https://amphenolprocom.com/products/filters

    Get an RF engineer on board to support you.



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