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- A more efficient technique to power home monitoring systems using controlled battery chargingPublication . Azevedo, Joaquim Amândio; Santos, Filipe EdgarHome energy monitoring has recently become a very important issue and a means to reduce energy consumption in the residential sector. Sensors and control systems are deployed at various locations in a house and an intelligent system is used to efficiently manage the consumed energy. Low power communication systems are used to provide low power consumption from a smart meter. Several of these systems are battery operated. Other systems use AC/DC adapters to supply power to sensors and communication systems. However, even using low-power technology, such as ZigBee, the power consumption of a router can be high because it must always be powered on. In this work, to evaluate power consumption, a system for monitoring energy usage and indoor air quality was developed. A technique is proposed to efficiently supply power to the components of the system. All sensor nodes are battery operated, and relays are used to control the battery charging process. In addition, an energy harvesting system based on solar energy was developed to power the proposed system.
- Impact of the antenna directivity on path loss for different propagation environmentsPublication . Azevedo, Joaquim Amândio; Santos, Filipe Edgar; Sousa, Tony Andres; Agrela, Jenny ManuelaLog-normal is a very common propagation model used to estimate the path loss introduced by a given environment. However, in most cases the parameters of the model are antenna specific. In this work, it is shown that the path loss exponent is highly dependent on the antenna pair used in the communication system. Large errors are introduced in the prediction of the path loss if the antennas are different from those used to obtain the parameters of the propagation model. An improved model is developed for the 2.4 GHz industrial, scientific and medical band to estimate the path loss exponent for different antenna directivities knowing the path loss exponent of a reference antenna. The model uses the antenna beamwidth and the antenna gain to obtain a parameter related to the path loss.