Electronic – Cell phone bluetooth range

The problem with consumption is only marginally related to the antenna in this case. The only dependency is that with a better antenna you can decrease the error ratio, reducing the total amount of sent data. But if you want to reduce significantly the power, you have to play with the power management options of the transceiver, the chapter 5 of the manual.

Probably you have already read it and optimised the application, but if you want to sacrifice range and reduce power, the most obvious solution is to lower the transmit power, as described in section 5.5 (page 18).

The cantenna reduces only the power irradiated in other directions, but not the overall power irradiated; moreover, changing the antenna, yes, can affect the power consumed by varying the antenna impedance and lowering the power transferred, but you pay it with a loss in efficiency.

IMO the best thing to do is to optimise the radiation surface of the antenna and then reduce the transmit power to the working minimum.

Note that if you decrease the power too much, it may result in a high number of lost packets, and then in a higher consumption.

I am having difficulty figuring out an effective way to connect the two antenna together and allowing them to pass the Bluetooth signals back and forth. There seems to be many methods, and I am not the most knowledgeable with RF antennas and such. I thought that perhaps an enlightened individual could give me a push in the right direction so I am not going about a random "witch-hunt" for a solution.

First, to test feasibility, simply connect the inside and outside antennas together, using something such as a pair of panel-mount coaxial connectors installed in the faraday cage - or better, a coupling barel inserted through the wall. This should cost little in time and money to validate.

Next, select components for a diode-bias RF switching scheme workable at 2.4 GHz, and install this between the antennas, so that by changing the DC bias voltage you can electrically connect or disconnect the antennas.

Optionally, add a filter to pass only the frequencies of interest.

There will of course be loss is such a setup, but by keeping the overall distances short it should be workable. Applying gain would be very difficult, as in practical terms you would need to figure out which device was transmitting and enable only that amplifier, which requires a realtime understanding of the protocol.