Electronic – nRF52832, using a chip antenna for short range purposes

The most cited paper on the subject that I could find is PCB design techniques for lowest-cost EMC compliance Part 1 (not free).

Though the part you're interested in is succinctly quoted in Best practice in circuit board design:

Armstrong recommends stitching at no more than λ/20, with stub lengths no longer than this. This is actually a very good rule for stitching any ground fill to the ground plane on a multi-layer design. λ is the wavelength of the highest significant frequency for the design (assume a frequency of 1 GHz if not know) where

f = C / λ

NB: C (speed of light) will be approx. 60% of free-space velocity for EM radiation propagating through a FR4 dielectric PCB.

Another technical note repeats this rule of thumb:

The common rule of thumb is to locate stitch vias no further apart than λ/10 and preferably as often as λ/20.

And gives some good reasons on why would would want to use via stitching/via fences:

There are numerous reasons to use ground via stitching on a multilayer PCB. Some of the reasons are:

• Prevention of coupling into nearby traces and metal pour.
• Prevention of waveguide signal propagation, shielding/isolation of circuit blocks, and the reduction of slot radiation from the edges of a PCB.
• Completion of a robust power distribution design. Reduction of series inductance to active and passive parts. For more detailed info on PDN (power distribution networks) in PCB, see [ 2 ].
• Signal integrity, in particular for signals that transition planes.
• Thermal reasons (not covered in this tech note).

With respect to your particular application, the WirelessUSB™ LP/LPstar Tranciever PCB Layout Guidelines state the reasoning more plainly:

The top and bottom layer copper pours provide an uninterrupted return path. This is maximized by the distribution of ground vias connecting the two layers. The internal ground plane of 4-layer designs also provide uninterrupted return path by connecting areas of copper that may otherwise be islands that do not contribute to the return path. The term “via stitching” describes the practice of placing evenly spaced vias around the board. Figure 9 shows a good distribution of ground vias with each via marked by a ‘+’. The row of more densely distributed vias along the top edge of the board is the applied antenna ground and is required to maximize the RF performance of the device.

I'd advise you constult the 'BLE examples' section in the SDK documentation to choose an appropriate example based, then follow these steps. I've chosen the Heart Rate Sensor example to run through here.

1. With the Keil pack installer, ensure you have the appropriate devices, drivers and example packs installed.
2. In the Pack installer, choose an example that uses the 'S110' soft device, and corresponds to an example you've found in the SDK. Choose the 'PCA100028' version.
3. Click 'Copy' to create a local copy of the project. It should open by default once you choose a location.
4. Once open, select the 'flash_softdevice' target from the dropdown.
5. Change the target options to use the appropriate programmer in the correct mode.
6. Change the flash download options to do a full chip erase. (You may also need to change the programming algorithm to 'nRF51xxx External Connection Board' for it to program without error.)
7. Confirm the options then flash the soft device to the board (You shouldn't need to compile anything at this point).
8. Change the target from the drop-down menu back to the example: e.g. 'nrf51422_xxac_s110' (The chip name is wrong, but it will still run fine since the nRF51822 supports the s110 soft device)
9. Set up the st-link debugger as you did before, except leave the programming algorithm as the 'nrf51xxx', and ensure it's only set to 'Erase Sectors' with the 'Reset and Run' active.
10. Compile the project and load program onto the board.
11. At this point, if you have the module attached to the motherboard, you should see One active LED and one flashing LED. The flashing LED indicates the device is ready for connection. You can connect to the device using the nRF mobile apps.

Feel free to add comments if you stumble across this and find problems of your own!