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  1. #1
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    External Antenna on Bluetooth module

    Hello ! I have a TDA7492 module with Bluetooth receiver. I have also spare 2.4GHz antennas. Is it possible in some way to replace the module PCB antenna with the external , for better range ? Thank you
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  2. #2
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    Re: External Antenna on Bluetooth module

    Yes, you can do this. Identify the feed trace of the printed meander monopole antenna on the PCB, disconnect (cut) the trace, and from there, using a thin 50 ohms coax cable, you can go to an external antenna, which I assume is also 50 ohms impedance.
    May exist the possibility to need an LC matching network on the PCB, but I guess that you don't have a Network Analyzer. But you can try without using any extra components and are chances to get good results.

    https://cdn.shopify.com/s/files/1/00...g?v=1546403345



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  3. #3
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    Re: External Antenna on Bluetooth module

    CSR8635 has 50 ohm RF port, the modules have additional matching circuit for the meander antenna.



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    Re: External Antenna on Bluetooth module

    Looking at the product photo: it's a shame that circuit designers don't understand how sensitive the placement of the RF module on the PCB is. They create a wireless product, and then ruin the range by bad antenna placement.

    I had investigated such a situation for 868 MHz and documented the antenna de-tuning here: https://muehlhaus.com/support/antenna/pcb-em



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    Re: External Antenna on Bluetooth module

    This example about wrong placement of an RF module is nothing compare to what the biggest electronics company in the world did about 17 years ago when designing their first wireless mouse using Bluetooth. The product was designed by the digital group of the company, which had absolutely no clue of RF design.
    So, they threw randomly a Bluetooth module (made by a different company) on a mouse PCB, tightened the screws, plugged it into USB, moved the mouse several times on the mousepad and ready, put it up for sale. There was absolutely no wireless performance test done.

    https://en.wikipedia.org/wiki/Apple_Wireless_Mouse



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