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WL1837MOD Single antenna placement - PCB layout.

Hur
Intellectual 435 points
Other Parts Discussed in Thread: WL1837, WL1837MOD

Hi,
I am planning to use WL1837MOD in single Antenna configuration. In the reference design of WL1837 both chip antennae have been used and they are more than 60mm away from each other. If I only have to use single antenna how far would it be placed from the module and what would be the characteristics of the RF trace to the antenna feed point. The device in which this module will be used has a form factor of 55mm x 35mm. Due to the form factor constraint i will need to modify the pcb layout  I haven't found any useful information regarding this so any help would be really appreciated.

Thanks.
Hur

  • 0
    Intellectual 435 points

    Hi,

    Please provide any help regarding the single antenna placement for WL1837mod module.

    Regards,

    Hur 

  • 0 in reply to Hur
    TI__Guru* 85400 points
    Hi Hur,

    The distance to the antenna is only important for reuse of the certification and the trace loss introduced by the long trace.
    We have certified the module using conducted method on the u.fl connector of the COM8 board so it’s the recommended to use the same length as original.

    Regards,
    Gigi Joseph.
  • 0 in reply to Joseph Gigi
    Intellectual 435 points

    Hi,

    The product for which I am using this wi-fi/bluetooth module has a small form factor (55mm x 35mm) approx.  The COM8 board design is about 76mm by 30mm which cannot be integrated into my application. I need to to use the module with a Single chip antenna and not 2 antenna as in the reference design. I need to place the chip antenna closer to the module and connect it with a 50ohm trace. Since i would be reducing the trace length so the trace loss should decrease...Is my understanding correct?

    Regards,

    Hur

  • 0 in reply to Hur
    TI__Guru* 85400 points
    Hi Hur,

    Yes it should decrease.
    The power that we have certified was on the module boundary.

    Regards,
    Gigi Joseph.
  • 0 in reply to Joseph Gigi
    Intellectual 435 points
    Hi,

    Since I will be using only antenna ANT1 in WL1837 module for communication. Is there any way to determine the power and its relation to the trace length? What can be minimum length of trace from the module to the chip antenna?

    Regards,
    Hur
  • 0 in reply to Hur
    TI__Guru* 85400 points
    Hi Hur,

    Please see the below response from our hardware expert:

    ***
    I recommend to use similar distance to the antenna at least as the u.fl on our module.

    Please do note that if the layout is exactly the same then no question asked the customer can get the reuse of the modular certification, once any change introduced there will be always some process with the TCB to get it reused/recertified – at least a cabinet testing – process where are short test cycle of test performed in order to confirm the original certification can be reused.
    ***

    Regards,
    Gigi Joseph.
  • 0 in reply to Joseph Gigi
    Intellectual 435 points
    Hi,

    I have another question regarding the placement of chip Antenna ANT1 that if it is placed closer to the WL1837mod does have any effect on the RF range or the performance?

    Regards,
    Hur
  • 0 in reply to Hur
    TI__Guru* 85400 points
    Hi,

    ***
    Yes distance to the antenna impacts the insertion loss.

    As an example the trace from the module to u.fl on the WL1837mod is ~0.3 dB, and as a rule of thumb every 6 dB are approximately double the range.

    As you understand having a budget of 110 dBm link( sensitivity + output power of 11B for example) the ~0.3 dB that you have to the antenna does impact significantly.

    More important is to keep the trace 50R and make sure that there is a matching before the antenna to make sure the antenna delivers the best optimal power transfer and maximize the efficiency.
    ***

    Regards,
    Gigi Joseph.