Long-range RFID emitter antennas for passive keyless entry systems: Page 2 of 4

October 10, 2016 //By Jorge Rodriguez
Passive keyless entry (PKE) is among the recent technologies introduced into the automotive sector one of the trendiest. No doubt! Touching the door handle or approaching to it and automatically opening is like dark magic.

The researchers followed two independent strategies to circumvent the materials' brittleness and achieve a higher magnetic field strength. They blended long highly permeable magnetic microwires with polymer bonded soft magnetic particles (Alma core).


Fig. 3: Emitter antenna core (Alma Core)

This approach allows for a reduction of the number of emitter antennas up to three folds. The resulting car architecture will drive significant cost savings that will further increase the PES adoption. In terms of material, wiring length and number of connectors could be reduced by a third, the same for the electronic drivers and amplifiers. Fewer components mean less probability of failure. Reducing the number of drivers will also limit overheating in their devices, which increase the reliability of the system. With respect to OEM, assembly time could be reduced substantially.    

It is known in the sector that aspect ratio (length/diameter) is a key parameter to achieve higher reading range. A longer antenna requires less power to reach the same magnetic field, lowering the energy consumption. The rod permeability of an inductor is not equal to the material permeability due to the big air gap where the magnetic field propagates.