Some history.....last December Ciseco started shipping the XRF v2.0. On the XRF v2.0 is the SRF v1.3 which saw the removal of the on board chip antenna. There were a number of benefits derived from the change, which were all covered in Matt's post at the time. One of these was that the complexity and cost of the SRF was reduced and this was immediately reflected in the bulk price of the SRF. Unfortunately due to the high cost of supporting less experienced users of the SRF the single unit option was dropped. However with some added disclaimers and pleas for the inexperienced to purchase other products it is back in the store as of today in quantities of 1 and upwards!
With it back in stock and available to all and sundry for the sum of £9.99 including VAT you'll be wanting to get the best performance from this small surface mount module. There are a few ways to do this.
The first is to use an 8.2cm wire whip antenna. Add a hole on your PCB close to the surface mount landing pad of the SRF antenna and solder the wire whip in place. Wire whip antennas seem to be the most robust solution to the problem of an RF antenna. They are the least affected by the layout of the board the SRF is to be attached to and therefore best.
The second solution is to add a chip antenna. A chip antenna will usually require tuning to the PCB layout to get maximum range (impedance matching). This is really only an option you'll want to consider if you want to make a product of your project and you want maximum benefit for minimum cost. We'll be covering more on the design and tuning of chip antennas in future posts, and Matt has published an example of a chip antenna layout in the Ciseco Github. Tuning requires selection of the three components used with the chip antenna. This can be done by trial and error or carefully calculated using some meaty formulae.
Third would be to add a socket for a larger external antenna. However the experience within Ciseco says that a wire whip will often produce better results than one of these more expensive bits of kit (the ARF however does love the new rubber duck, you'll get close to 20db more)
For now my advice if you're using an SRF with your own board is to............whip it, whip it good!