Meander antenna question when using nRF51822

[MANGO]

Hi, I just bought the PCA10031 nRF51422 based USB dongle and PCA10028 nRF51422 based development board.

The difference between nRF51822 and nRF51422 was the ANT protocol stack.

My client wants to choose the nRF51822-QFAA for his personal reasons

and he wants to use the meander antenna which is drawn at the PCA10031.

My questions are;

1. Although the nRF51822-QFAA and the nRF51422 are similar,

I want to know whether it is fine to use the same values for the RF and the antenna components, the RLC values.

I'm planning to use the FR-4, 1.6mm thick, 2-layered PCB.

Can I use the same components, which is described in the PCA10031's schematic, when I work with nRF51822-QFAA?

// Edited 2017.05.09 - Summary & Compare referring Jørn's answer

nRF51822 Product Spec 3.3

nRF51422 Product Spec 3.1

2. I just want to double check.

Compared to the Inverted F antenna, the meander antenna, which is drawn on PCA10031, doesn't connect the antenna trace to the ground plane, right?

3. By looking at the Digi-key number, the PCA10028 (Rev 1.2.0) used FC-135 32.7680KA-AC-ND, a product that uses 9pF as the load capacitance.

In this blog,

C1 = C2 = 2Cl - C_pcb - C_pin // C_pcb + C_pin is approximately 4 pF

I expected the capacitor values to be 14pF. However, the schematic tells that 12pF capacitors are populated.

Is there a reason for choosing the 12pF, such as

reducing the type of items for the pick and place machine or that Rev 1.2.0 board's C_pcb + C_pin value is approximately 6pF?

-Best Regards, MANGO

[Jørn]

Keep in mind though the C_pcb is dependent on layout, board dimensions and substrate. If correctly designed it's impact shouldn't be very large, and the dominant capacitance would probably be the XC1 and XC2 pads. The traces of the DK are longer than strictly necessary due to the solderbridges, and the solderbridges themselves would also add some extra capacitance.