4.3 WBZ35x Module Placement Guidelines

For any Bluetooth Low Energy/Zigbee product, the antenna placement affects the performance of the whole system. The antenna requires free space to radiate RF signals and ensure it is not surrounded by the ground plane. Thus, for the best PCB antenna performance, the WBZ35x Module must be placed at the edge of the host board.
The WBZ35x Module ground outline edge must be aligned with the edge of the host board ground plane (see the following figure).
A low-impedance ground plane for the WBZ35x Module ensures the best radio performance (best range and lowest noise). The ground plane can be extended beyond the minimum recommendation as required for the host board EMC and noise reduction.
For best performance, keep metal structures and components (such as mechanical spacers, bump-on and so on) at least 31.75 mm away from the PCB trace antenna (see the following figure).
Do not place the antenna on the WBZ35x Module in direct contact with or close proximity to plastic casing or objects. Be sure to keep a clearance of 10 mm in all directions around the PCB antenna (see the following figure). Keeping metallic and plastic objects close to the antenna can detune the antenna and reduce the performance of the device.
Exposed GND pads on the bottom of the WBZ35x Module must be soldered to the host board (see Example of Host Board on Top Layer figure in the WBZ35x Module Routing Guidelines from Related Links).
A PCB cutout or a copper keepout is required under RF test point. See WBZ35x Module Packaging Information from Related Links.
Copper keepout areas are required on the top layer under voltage test points. See WBZ35x Module Packaging Information from Related Links.
On the other hand, the entire region except the exposed ground paddle can be solder-masked.

The following figure illustrates the examples of the WBZ35x Module placement on a host board with a ground plane. Refer to the following figure for placement-specific guidance.