Premo Nanotech Magnetic Materials Allow Long Flexible Emitter Antennae for Automotive Electronics

PublishTime： 2021-05-08 Article Source：PREMO

The Alma™ Core Technology for Car Keyless Entry Systems saves installation, cables, electronic drivers and reduces component count with savings per vehicle over 100 USD.

The product is designed to be flexible and unbreakable thanks to a combination of Solid Echelons, Polymer Bonded magnetics, and High Magnetic Permeability nanowires.

A Team of Scientist from Madrid CSIC ( Superior Council of Scientific Research), led by a renowned expert in Magnetism Ph Dr. Manuel Vazquez Head of the Group on “Nanomagnetism and Magnetization Processes”, researchers of UCIII Madrid, and a team of materials scientist and technologists at PREMO Innovation Center in Málaga, have developed a Technology intended for LF emitter antennas in the range of 20KHz to 134KHz that overcome the limits of conventional ferrite cores that are fragile and brittle and cannot be manufactured reliably in long forms. After 3 years of work and more than 1M€ in private and public funding, the team is announcing the first industrial solutions of the new tech.

Metallic alloys of Fe, Ni, Co have been largely used for low-frequency magnetic application thanks to their very high magnetic permeability (x1000 compared to ferrite) and their relatively high Magnetic Saturation ( x3 compared to ferrite). High-frequency losses related to eddy currents have been relatively well managed in amorphous and nanocrystalline structures or in very thin laminated packs by layers electrically isolated from each other. None of these solutions work for long flexible emitter antennae due to magnetostriction an unwanted effect that produces significant changes in electric performance when the cores are deformed.

The production of amorphous and nanocrystalline nano-wires keeps both positive effects (high permeability and saturation) and avoids magnetostriction and losses by Eddy currents due to the extremely low cross-sectional area and isolation. The Nanowires are distributed in a Polymer Bonded Magnetic matrix loaded with isolated ferrite nanoparticles as per Figure 0.

Fig 0

Fig 1,2,3

Existing solid single-core ferrite antenna has to be installed around the vehicle (typically 4-5 per vehicle for full coverage). Figure 1 shows the radiation pattern of these so-called Short Range Emitter Antennas.

Recently, in a pressure to reduce performance and cost, automotive Tier 1 company are designing systems with so-call Mid-range antennae, that still use solid long monolithic ferrite cores and increase reading range as per Figure 2 pattern. Nevertheless, those antennae may exhibit critical mechanical and reliability performance as the ferrite cores are typically longer than in Short-range ones, and flexion and torsion resistance drop significantly as per Figure 4.

Fig 4

The solution developed by Premo -led researchers is fully flexible, unbreakable, and can be as long as necessary. Three groups of international patents have been filed:

- Innovative Nanoparticle Polymer Bonded Flexible magnetic core ( Fig 0).

- Innovative High Permeability nanowires ( Fig 0).

- Innovative Ferrite Echelon Articulated constant gap Chain ( Fig 4.2).

- Automatic Process to produce long elongated antennae.

Fig 4.2 Link Ferrite Premo solution

The ferrite core is then assembled to form a chain that is over-molded with PBM that keeps the product flexible and guides leakage magnetic flux along with the core.

The air gap between echelons or core links is constant and the flux redirected inside the coil.

Fig 5

The new AF series is presented in three standard lengths (AFS 322mm, AF 379 with a center post for fixing on chassis with an air gap to metal, and AF ULR with 554 mm as per Figure 6)

Fig 6

Field and laboratory tests show that the AFS ULR configuration can generate signals with ranges over 30meters with 722mV/App/m sensitivity and generating a field at 3m of 123 dBµV/m opening the option to use is in Car to Car (C2C) long-wavelength safety communication of short messages such as alarms or instructions in Platooning.

The product can reduce the number of antennas required in a Keyless Entry system from 5 to just 2 or even 1 with considerable savings in:

- Antennas costs.

- Wiring, installation, cable harnesses, and connectors.

- Electronic drivers and amplifiers.

- Weight, space, and component count.

Fig 7

The product is designed to be waterproof IP67 with a standard low-cost EWCAP type universal connector integrated to ease installation, reliability, and connectivity. The product has been qualified for AECQ200 and is available with or without tuning a resonant capacitor.

This family is compatible with most ECU reference designs from NXP like MPXY8300 family, TI, or Atmel (Microchip) like ATAK51004-V2 among other semiconductor manufacturers.

The mass production manufacturing process for antennae using this kind of flexible magnetic cores has been also developed and patented by Premo. The process handles the cores without damaging them, and also able to wind the enameled copper wire around it at high speeds, controlling pitch and winding window with automotive quality performance.

The ownership of the core technology and the process allows Premo to offer a full set of solutions to the market. Additionally, full customization is possible, a requirement coming as mandatory in most of the car brands. Electrical performance, field strength, mechanics, interface or field robustness can be fully customized, depending on the car segment, geographic area, or market.

This kind of solution is being qualified right now in major tier 1’s worldwide, being Premo a preferred supplier on key ones, with mass production launch ongoing for several specific part numbers.

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