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Small Size 2.4 GHz PCB IFA antenna

Renat Martin
Prodigy 20 points

Hi,

I'm working with document of "Small Size 2.4 GHz PCB antenna" (swra117d.pdf), in this document you show how to do the design of this antenna. 

I have a question about the lisence of this one, is an "open source" antenna or is protected with a patent. I would produce a prototype for my project and I need to solve this trouble before do a massive production.

Thanks 

Renat

  • 0
    TI__Expert 4435 points

    Renat,

    As one of the designers of the PCB antennas form TI,  it is good to here an engineer who recognizes they should start the design with first selecting the antenna.   This antenna is open source and tuned for a 50 ohm input impedance.   Like all monopole antennas the ground size sets the antenna's performance for high efficiency.  So not only copying the dimensions stated in the app note.  Please obsever the ground size.   This way you will see the same performance. 

    The other key point is the bandwidth of this antenna is set for a low Q.  When placed in an encloure you should expect some frequency shift.  We have app notes which show final tuning of antenna resonace for the highest efficiency.    Words of caution if you change the board thickness you will effect the antenna matching.    So observe this board thickness is 0.8mm  (31mil)  2-layer baord thickness.

    Regards,

  • 0 in reply to RRS
    Prodigy 20 points

    Thanks for answer so fast, your info is very useful

    Renat

  • 0 in reply to RRS
    Expert 1925 points

    Hi, RRS,

    We're going to adopt this antenna too, I'm glad to find your early reply still helpful, below are some more questions:

    1. About the ground size, what if we can't make it same as in the USB dongle design? is there a limit range?

    2. About the app notes which show final tuning of antenna resonace for the highest efficiency, seems I can't find it, please help.

    3. In the document, it says: "To compensate for a thicker/thinner PCB the antenna could be made slightly shorter/longer.", how to do that?

     

    Thanks.

    Zhu

  • 0 in reply to zhu
    TI__Mastermind 30890 points

    Hi Zhu,

    1. Since this is a monopole antenna design; one quarter wave is the actual antenna element and the other quarter wave is the GND plane. So the GND plane should be at least a quarter wave distance. Increasing the GND plane size will have more effect on the natural impedance of the antenna and the radiation pattern.

    2. Use a VNA, to find the optimum length of the antenna and remember to measure the antenna in it's final packaging.

    3. Same as 2. but just fine tune the length since the impedance will vary slightly when changing the pcb thickness. Measure the VSWR or RL.

    Regards,

        Richard 

  • 0 in reply to RGW
    Expert 1925 points

    Hi, Richard,

    Thanks for the replying.

    So, increasing the GND plane would have negative effect, right?

    I want to verify your reply as answer, but can't find that button, sorry.

    Zhu

  • 0 in reply to zhu
    Prodigy 30 points
    Nice work! You touched on a topical issue. I would appreciate if you'd written about how to fill a form online. By the way, if anyone is facing a problem of filling a form, I've found a template here http://pdf.ac/7ERzS4. You also can esign the form and fax it.
  • 0 in reply to zhu
    TI__Mastermind 30890 points

    Hi,

    Ideally, the monopole antenna GND plane should be a quarter-wave and if this is increased then the additional ground could have a negative effect (higher directivity).

    Regards,

       RIchard