5 Replies Latest reply on Jun 10, 2019 3:07 AM by user_4160961

    Antenna gound plane

    user_4160961

      Hi All.

      I am testing a CYBT-483039-02 module and something brings my attention. Does this module (as is the case with BLE modules from other manufacturers I´ve tested) need a host PCB ground plane to achieve the expected Tx power? When I review the available antenna design documentation, all I find is recommended clearance space details but nothing about the need of a ground plane to bust the RF transmitted power. Is maybe this antenna chip it includes different from traditional trace antenna solutions in which a ground plane on the host PCB is mandatory? Thanks

        • 1. Re: Antenna gound plane
          BoonT_56

          The CYBT 483039 module uses a chip antenna which we have already incorporated the RF ground keep-out area onto the module. Upon mounting onto a host board, the area below the "Antenna Area" (refer to Fig 2 of the datasheet) of the module should be cleared of copper so as not to create discontinuity. This is probably the most important point to take note.

           

          If you have space on your board, then it "will be nice" to place the module in one corner as well, with continuous ground extending out by another 5mm.

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          • 2. Re: Antenna gound plane
            user_4160961

            In the document 002-23993_CYBT-483039-02_EZ-BT_TM_XR_WICED_R_Module last reviewed by Jan 4th, 2019, when they talk about antenna design and the Host PCB board, ONLY the Antenna Area Keepout and the module area prefered placement is being addressed. Nothing regarding a Host PCB ground plane or "... continuous ground extending out by another 5 mm..." is mentioned. That's the reason why and since in my project, keeping the 12,75x 18,59 mm footprint is almost mandatory, my question again is if: by using a chip antenna (as is the case in this module) you eliminate the need of a Host Board ground plane or not? Thanks

            • 3. Re: Antenna gound plane
              XinghaoZ_26

              To ensure a better RF performance, no metal should be located beneath or above the antenna area, only bare PCB material should be located beneath the antenna area. To maximize RF performance, the area immediately around the Cypress Bluetooth module chip antenna may contain an additional keep out area, where there are no grounding or signal traces. The keep out area applies to all layers of the host board. Please refer to Figure 2 and Figure 4 in the datasheet for details.

              For the other area of your host PCB, you can design with your own application. It doesn't need a host board ground plane.

              • 4. Re: Antenna gound plane
                BoonT_56

                I think my colleague has pointed out the key point here. Wherever you stick the module on the host board, the area below the "Antenna Area" is preferably to be cleared of metal, as it will influence/negate the radiation pattern. Irregardless of the antenna type, ground plane is part and parcel of the design in fact. And so a simple reply to your question is: Yes, you still need a ground plane.

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                • 5. Re: Antenna gound plane
                  user_4160961

                  Thanks BoonT_56. And since in my project, minimun footprint is a must, having a ground plane not protruding over the shield size would be still valid to build the antena parcel?