Modern Bluetooth dongles are designed to be low powered and do not account for any obstacles between the dongle and the device to be used. For most dongles, a concrete wall would reduce the range considerably up to the point that most dongles only really work within the confines of a single room.

Similarly, there are many attempts to be found on the Internet where people attempt to hack Bluetooth dongles and extend their range by attaching a better antenna to the dongle. Whilst the principle seems to be sound, for high frequencies such as , the correct and corresponding antenna length is rather small such that most of the results obtained from these hacks are wildly unstable and range from minimal gains to catastrophically bad results.

The following tutorial presents some low cost equipment that can be used to obtain a long range Bluetooth dongle that should be good to use in multi-story / multi-room building.

• Sena USB Bluetooth Adapter UD100-G03. The Sena UD100-G03 is an industrial grade class 1 Bluetooth device that is designed to work over very long ranges (advertised as officially) provided that the connecting device is also a class 1 Bluetooth device. In case the connecting device is not a class 1 Bluetooth device, then a range falloff should be expected, however the dongle is still very powerful compared to more modern and low-powered counterparts such as the coin-sized Bluetooth adapters.

• Sunhans eSunRC RC WiFi Signal Booster, and Dual Band Wireless Signal Amplifier. The Suhans amplifier is a little gem that is a little costly but a device well designed that is even able to commute between and that is primarily geared towards boosting done signals. Nevertheless, for its size, the gain as well as its large voltage input range, combined with its capability of boosting some of the most common commercial grade frequencies ( and ) makes the amplifier a must-have for anyone that wishes to amplify right about any electronics signal ranging from simple wifi routers and up to industrial drones. This is a thing of beauty!

• RP-SMA to SMA male-to-male (male to female, in layman terms). The main reason to get a very short RP-SMA to SMA adapter is to avoid any losses incurred when connecting the Bluetooth dongle to the amplifier. An RP-SMA to SMA adapter seems to be the shortest available option.

The setup is quite simple:

• the Bluetooth dongle Sena UD100-G03 is connected via USB to the PC, perhaps with an optional USB extender cable,
• the Sunhans adapter is connected via the RP-SMA to SMA adapter to the Bluetooth dongle,
• the antenna pin of the Sunhans adapter is connected to a antenna.

Note that the antenna preference has not been mentioned mostly due to the same argument that at very high frequencies, there is not much that an antenna can do (this is compared to, say short wave radio where the antenna size scales with the reception and transmit benefits). There are many antennas available and any antenna that connects to a wireless router using the b or g bands should really be more than fine. Then there are antennas that are advertised at ridiculously high gains but in practice most of these antennas do not live up to the standards.

Nevertheless, note that for this project an omnidirectional antenna has been preferred but in case the long range Bluetooth device is supposed to connect to a certain device at a given point in space, a directional antenna such as a Yagi could be used in order to reduce the waste that an omnidirectional antenna produces and focus the signal in one single direction.

Putting it all together, the following contraption is obtained:

As empirical results, the dongle just passes through everything, concrete, metal doors, it even beams outside the house without a hitch. Even though the Sena USB Bluetooth Adapter UD100-G03 is just a Bluetooth 4.0 device without the extra, often superfluous, enhancements added by more modern standards, the signal strength is so high that any benefits from ulterior additions to the Bluetooth standard are negligible. You have to consider that the UD100-G03 combined with the Sunhans should provide up to about a kilometer of signal in plain sight without obstructions such that even in a walled home the signal should still be strong enough to reach any corner of any house.

For the Sunhans a transformer has been used even if the Sunhans is rated at maximum . Similarly, even though the Sunhans can be powered from an USB port at , an external transformer at has been chosen in order to avoid USB power instability and to not put any further load on the USB port of the computer. Even so, USB ports are rated at a few whereas the Sunhans is said to draw up to which vastly exceeds the capabilities of a PC USB port.

The device has been sellotaped to the back of a monitor and happily provides a Bluetooth radiation beacon that can reach any device in a very large area. No more need to purchase expensive headsets or Bluetooth PCI cards to obtain the exact same result.