I have been looking at the range of the modules.
I was having problems connecting from the first floor of my house to the ground floor. Knowing that Low Power 2.4 GHz has trouble passing through obstacles, I was thinking this was simple attenuation.
Looking at the antenna design further though, I believe there are some fundamental antenna design considerations to take into account.
The module antenna seems to be 1/4 wave monopole (via a QFN balun) of the inverted F design.
I'm not sure exactly where the ground plane for the antenna is (I can't see it, but it has to be there).
So, things to take into account to get the best range from the module.
1) surroundings.
By this I mean things close to the antenna. Material close to the antenna will effect it's impedance, and hence it's matching (and thus reflected power). This includes plastic, wood, people, and metals. Antennas work best for the environment they are matched to (at design time). I don't know if the antenna was designed for a free air environment, but placing the module on a surface or in an enclosure can cause problems.
One reason I believe that I have some problems with range to a door sensor, is that it is attached to a door! Worse, the door is a steel door. Short of attaching a wire antenna, there is not much I can do about this though.
2) Ground Plane
A monopole antenna needs a good ground plane, but it must be a minimum distance from that ground plane. A steel door for instance a few mm from the antenna will not be good. I also noticed the coin cell slightly overlaps the antenna area. moving the coin cell may help improve range, or using the module with a separate supply (to remove the coin cell completely) may help. Avoid placing the module directly on a surface (close to the antenna), raising the module up from a surface a few cm could make a difference.
3) Shielding
The antenna must not be shielded by something conductive (like a faraday cage). An example would be a metal fridge or freezer, or a metal range hood. A metal wall box would be bad, use a low voltage plastic one. You can put the modules inside a metal enclosure, but the range is likely to be severely reduced.
4) Attenuation
Objects between the module and gateway will refract, reflect and attenuate the signal. Try to avoid objects in the signal path if possible. I know, people, walls, doors etc. are not something that can be planned for, but if you have the choice, minimize obstructions as far as you can. This could be as simple as avoiding the areas of walls/doors that have wood/metal behind them (like wall studs for example).
5) Orientation
An ideal monopole is isotropic (ie radiates in all directions equally), in reality this is rarely true. so the module/gateway will have greater range in some orientations than others. Due to the principal of reciprocity, if the transmit signal is better in one direction than another, then the receive gain will also be better in the same direction (ie the transmit and receive functions for an antenna are the same). This is why boosting the power/gain at one end of a radio system does not work, you have to either boost both tx power and rx gain, or boost tx power or rx gain at both ends.
Slightly adjusting the orientation of a module/gateway can make a connection better or worse, and is worth some experimentation with long range modules.
Polarization may also be important. Monopole antennas are polarized in the plane of the antenna, usually horizontal, or vertical. If the polarization is different between a module and the gateway, there will be a signal loss. Theoretically a 90 degree difference (ie module vertical and gateway horizontal) could result in a 20dB signal loss. In reality it's probably less than this, but it is a factor!
In summary, I have found that some module I though were out of range, could be brought back in range by adjusting the positioning/orientation of the gateway. this will be a compromise, but it is worth considering in the placing of modules/gateways.
The quoted 200m range is obviously under ideal conditions, and is the maximum possible. In the real world, a range of 30m would be considered good.
These are my thoughts on range and antenna considerations, it's a long time since I was designing antenna's, so please excuse any errors, also feel free to correct any bad assumptions or mistakes I have made.
FYI I believe the design of the antenna is based on this:
http://www.ti.com/lit/an/swru120b/swru120b.pdfI hope you find this useful.