QN9080-001-M17(SIP) Antenna design for no ground plane

[tpgurtpgur2]

Hi

I am trying to make a very small BLE device using a QN9080 SIP. Since there should be no ground plane on the PCB because i am designing in a special situation, i connected all ground pins of the circuit with traces.

The datasheet has guidelines only if a ground plane is present. If there is no ground plane like mine, how do I connect the antenna function pins (Pin 48, 49, 50) and do I need an additional antenna trace or small ground plane or chip antenna?

I tested both with and without a ground plane, and there was a difference in RF performance, and the performance decreased when there was no ground plane.
(Please check the attached photos of both test layouts.)

I would appreciate it if you could provide a guideline for maintaining the same high RF performance even in the absence of a ground plane.

Thank you.

Best regards.
Oh.

[ryan_xu]

HI Oh

can you share the your test result that test done on both of boards?

in fact, we don't recommend that layout the no ground plane on the PCB, you know a complete GND is important to ensure RF performance and power performance, 

Anyway, what mode of antenna in your application? I guessing that internal antenna is used, right? if so please see my suggestion in below,

1. increase the line wide for those GND trace connection,

2. layout a few of gnd shape on RF GND(48,49,50) pin and connect it as following,

Best regards

Ryan