Mid-range antenna problems solved with magnetic emitter

9th October 2018
Alex Lynn

Manufacturer of inductive components, Premo, has announced the LFAD-Series (Diabolo-shape) antennas, providing up to 50% reduction in length aiming to produce same H-field with a different L/D core relationship. Most of the LF antennas in the market have a length 70 to 80mm for standard range, 150 to 170mm for mid-range and 250 to 350mm for long-range (Alma-Core).

Over the last couple of years, mid-range antennas with a sensitivity of about three times the standard ones, have become more and more popular, with demand to provide a wakeup distance around four to five meters. 

The antenna performance in term of mechanical robustness, resonance frequency variation versus temperature and waterproofing have been the most important headache for the designers.

Premo has designed and patented a new concept of emitter antennas that aims to solve these handicaps with greater reliability without compromising the cost.

Therefore, the technical challenge is achieving all the advantage of mid-range and long-range antennas without the above-mentioned drawbacks of brittleness, costly materials, processes and investments and critical temperature and mechanical performance.

Diabolo antennas have set the goal to combine all the good features of mid-range antennas while preserving and keeping all the good features of the short-range antennas (cost effective, mechanically robust and thermally stable). 

Premo is using a Core with a Variable Cross-Sectional area that is maximum at both extremes of the antenna and minimum at the centre of the antenna where the winding is located. The antennas typically meet the AEC-Q200 (specific automotive quality standard) and waterproof specs from IP54 to IP69K standards due to their specific packaging (rugged plastic box filled with polyurethane resin, PA-LPM protection, combination of both materials and HPM (high pressure molding) in PBT GF20-30 for IP69K), also provide a much better drop, bending and torsion test limits.

The shape simulation below shows the much higher induction (red) in the minimum section area:

A wide range of values are in the catalogue of LFAD-Series and under demand, from 160uH to 500uH, for 20, 125 and 134.2kHz (with or without capacitor and resistors inside, under demand).

Samples will be available by end of Q4.

Premo will display their innovations at electronica 2018, Munich, Hall B3 Booth 548.

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