International audienceReconfigurable directional antennas (RDA) bring new opportunities to reduce data collision in wireless sensor networks (WSN). In this letter, a new reconfigurable directional antenna-based receiver-Initiated cycled receiver (RDA-RICER) medium access control (MAC) protocol is proposed for WSN nodes equipped with switched antennas. A low complexity and energy efficient scanning process is embedded in RDA-RICER to identify the direction providing the highest received signal strength Indicator between two nodes. OMNeT++ simulation results for a single hop network show that data collision rate can be drastically reduced compared with related MAC protocols, leading to a significant decrease in energy consumption. Our approach is also validated in the field using WSN platforms equipped with a four-direction RDA, and powered by solar cells
This work presents the use of a three-element radiating structure for circularly polarized Low-Power Wide Area Network (LP-WAN) communication with space. The proposed structure has a 72 mm × 72 mm × 12 mm compact size with Right-Handed Circular Polarization (RHCP) and a 120∘ wide beamwidth radiation pattern. Printed on low-cost FR4 Epoxy substrate, a feeding network circuit based on Quasi Lumped Quadrature Coupler (QLQC), it achieves a −0.6 dB insertion loss and a very compact size. The final structure has a 69% total efficiency and a 3.14 dBic realized gain.
International audienceThis letter presents a reconfigurable antenna for mobile terminals with extended band coverage obtained by using a digitally tunable capacitor (DTC). The antenna structure is matched permanently over high frequency bands including DCS/PCS, UMTS, LTE 1800/2600, and 3.5-GHz bands. Concerning the sub-GHz bands, several reconfigurable states enable a full coverage of LTE 600/700 and GSM 850/900 standards, as well as expected spectrum reallocations for 5G communications. With dimensions of 40 ×10 ×6 mm3 for the antenna and 130 ×70 ×0.8 mm3 for the whole printed circuit board (PCB), this structure is compatible with any mobile terminal
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