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CC1101 868MHz PCB antenna

Jerome Martin
Intellectual 430 points
Other Parts Discussed in Thread: CC1101

Hello,

I have to design an antenna at 868MHz, but I have very little space on the PCB. The PCB is vertical, and at the top (perpendicular to the PCB) there is a big metal plate. I need to put the antenne on the right edge of the PCB.

Let's say this is my PCB :

This design could be fine, but it is too wide. I can have 1cm x 7cm, or something of the same space but surrounded by the PCB ground plane (and with components).

I have tried an inverted L antenna, but the performance is not very fine...

Is it possible to do a dipole antenna directly into the CC1101, without any balun (or with...) ? I have tried it with wires (shaped as S to keep the 8cm per wire in a space of 1cm x 3.5cm) and it looks fare better than my previous antenna...

I couldn't find anything about dipole antenna for the CC1101. Does that mean it is a bad idea ?

Thank you.

 

 

 

  • 0
    TI__Expert 3595 points

    LPRF Antenna Selection Guide

    Has a lot of information on antenna selection for sub-1 GHz systems.  You might look at the chip antennas for space, but there is a cost downside to them.  Dipoles are going to be bigger than inverted F antennas, so that is probably not the direction to go.

  • 0 in reply to Chris M
    Intellectual 430 points

    Thank you for posting, but I would appreciate a lot answers to my questions.

    I have already read all the litterature from TI, and I would not have posted if I had found answers to my questions. If you do not understand them, I can try to explain my problem differently.

    Thank you for your help.

  • 0
    TI__Mastermind 31610 points

    Hi,

    If you design a dipole antenna that shall be connected to CC1101 it is a good idea to enter a differential filtering network between the CC1101 and the dipole to supress the harmonics in order to pass ETSI & FCC requirements when operating in the Tx mode. 

    Keep the elements of the dipole antenna similiar to each other otherwise the harmonics will increase and the output power will decrease.

    Regards,

       Richard

  • 0 in reply to RGW
    Intellectual 430 points

    Hello,

    Thank you for your answer. I really look forward to the dipole reference design. I made a PCB dipole antenna like this :

    I connected it directly on the output of the CC1101, and the emitted power is more than with my other antennas.

    Could you give more information about your reference design ? Do you have a piece of schematic ? a shape of the antenna ? I need to do a prototype as soon as possible...

    Thank you.

     

  • 0 in reply to Jerome Martin
    Prodigy 90 points

    It is good idea,but how about to make a loop antenna directly on the output of the CC1101.Can it work better than dipole

  • 0 in reply to kun_nan shih
    TI__Mastermind 31610 points

    There are no benefits for a loop or dipole antenna for the CC1101 since filtering is required between the antenna and CC1101 for the design to be approved for FCC & ETSI use.

    Regards,   Richard.

  • 0 in reply to RGW
    Prodigy 90 points

    Dear Richard:

      How about to add  LC filter between the loop antenna and CC1101 and Can it  pass FCC &ETSI??

     

      

  • 0 in reply to kun_nan shih
    TI__Mastermind 31610 points

    Have tested with adding differential filter but when the harmonics levels fulfilled the regulatory requirements, the component count was similiar to the standard discrete solution we have today so the benefits of using this topology were removed. For best performance, keep with the standard discrete WW inductor solution and use DN024 antenna.

    Regards, Richard. 

  • 0 in reply to RGW
    Prodigy 90 points

    But if my mechanial is round and the length is about half an wavelength . Can I use loop antenna around the mechanical though you said the components count is similar to DN024 the standard discrete solution.But  In some direction loop antenna antenna gain is better than monople and the space is more suitable than monople that need extra rectangular space . Is it right?

  • 0 in reply to RGW
    Prodigy 90 points

    Dear Richard:

      According to the loop antenna,can you give us the component value that have tested with adding differential filter  fulfilled the regulatory requirements

    our email is oliver@biosensetek.com. thank you or can you provide any application note for CC1101 loop antenna(868/915)