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 it must not be surrounded by the ground plane. Thus, for the best PCB antenna performance, it is recommended that the WBZ45 module be placed at the edge of the host board.
It is recommended that the WBZ45 module ground outline edge be aligned with the edge of the host board ground plane as shown in the following figure.
A low-impedance ground plane for the WBZ45 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 the 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 as illustrated in the following figure.
It is recommended that the antenna on the WBZ45 module not be placed in direct contact with or in close proximity to plastic casing or objects. Keep a minimum clearance of 10 mm in all directions around the PCB antenna as shown in 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 WBZ45 module must be soldered to the host board (see the Example of Host Board on Top Layer figure in the WBZ45 Module Routing Guidelines from Related Links).
A PCB cutout or a copper keepout is required
under the RF test point (see WBZ451 Module Packaging Information from Related
Links).
Copper keepout areas are required on the top
layer under voltage test points (see WBZ451 Module Packaging Information from
Related Links).
Alternatively, the entire region, except the exposed ground paddle, can be solder-masked.
The following figure illustrates the examples of WBZ45 module placement on a host board with a ground plane. Refer to the following figure for placement-specific guidance. Figure 4-6. Module Placement Guidelines
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