There is an ever growing interest in RFID technology given its ability to associate with remote sensors. The market of the spirituous beverages, particularly the most expensive ones are a target for the application of RFID tech. The low cost associated to the RFID tags create an opportunity to embed intelligence into the bottles without increasing the cost burden to the producers.

The challenge to create an antenna for a RFID tag to be embedded into bottles has already been addressed by some researchers and different solutions have been proposed, while none has shown an effective test with a RFID reader. Some solutions presented place the antenna into the bottle neck, or even in the cap, this is reasonable for glass bottles, but for plastic bottles the integration has to be into the body of the bottle, which was proposed in.

The antenna is based on a dipole with a matching inductive ring in order to match the RFIC input capacitance. The dipole approach was chosen given the good bandwidth characteristics of these kind of antenna which promotes robustness to the environment changes. The antenna was simulated in CST Microwave Studio starting with a simple design in and open environment with only the paper substrate as shown in.

We then designed a bottle considering the glass and liquid. Since we couldn’t measure with accuracy the permittivity of liquids such as wine, we used water to model the beverages since this is the best approximation. Due to the liquid presence, most of the energy was being absorbed by it and therefore the radiation efficiency of the antenna was extremely low, rendering it almost unusable. Due to that we added a reflector plane behind the bottle and redefined the antenna dimensions in order to obtain the pretended resonant frequency, in this case 866 MHz.

The solution proposed to overcome the RFID problem around liquids was to place a reflector plane behind the bottle. By doing so, we were able to increase the directivity of the antenna and slightly reduce the energy absorbed by the liquid inside the bottle, , which was clear from the increased communication range of the tag, while not affecting the bandwidth and resonant frequency of the antenna.