The overall dimensions of the NFC tag with the antenna might be important for particular use-cases. While the size of NFC tags and chips are in millimetres the size of NFC antennas is usually in centimetres. Our measurements confirmed that 9mm coil NFC antenna in PLM has NFC reading distance 5-25 mm that is satisfactory taking into account the miniature dimensions of the antenna used. In ALM the communication distance is 59 mm in open air and 35 mm in metal housing.

PLM results – various NFC tags were connected to 9mm micro coil NFC antenna and tested with various NFC phones used as NFC readers. The reference point for testing has been set based on the exact position of the particular phone’s NFC antenna.The table below shows the measured value of induced input voltage (Vind [Vpp]) in the distance of 5mm from the reader (NFC Forum position 100) and the maximum communication distance (the distance at which the tag still responds to a command from the reader). In PLM, 9mm coil antenna has inductance value 1.2 µH (@13.56 MHz).

NFC reading distances of 3 NFC tags using 9mm coil NFC antenna measured on 4 NFC smartphones

Electrical features of the micro coil antennas were measured in open air and in metal environment (50 x 30 mm Cu plate placed at the distance of 1 mm above the antenna). For ALM the inductance of the antenna was measured in pulse mode which corresponds to applications using the antennas in ALM. We specified overall rms value of the current flowing through the antenna during the measurement (“mA rms”). In PLM, 9mm coil antenna has inductance value 1.2 µH (@13.56 MHz).

Electrical features of micro coil NFC antennas

Planar antennas have limitations to communicate in metal covered objects.  

Narrow but long rod ferrite micro coil NFC antenna emits the energy in the horizontal axis very strongly. The intensity of the magnetic field reaches its maximum at the ends of the ferrite core. The below picture shows how the magnetic field passes through the narrow (0,05 mm) slits of the metal cover and gets back into the ferrite to be closed into loops.

Micro coil NFC antenna in metal housing – the emitting diagram

Coil antennas have stable performance in metal environment. Inductance of 9mm coil antenna when supplied with current of 100mArms in open air is 1,25µH while in a metal environment is 1,2µH
From approximately 3 mm distance between a metal plate and the antenna the influence of the metal on the antenna inductance is negligible, see 9mm coil antenna results in the graph below:

Properly designed metal housing may even increase the effectiveness of the antenna performance.

Video Micro Coil NFC antenna performance in metal objects

Micro Coil NFC Antennas support ALM and PLM

• tiny devices – under skin glass tubes, human and animal implants for NFC tags for identification and bio-signals monitoring
• metal housing objects and complicated electronic environments (ALM and PLM)
• micro paying wearables – rings, watches, key fobs, microSD cards (EMVCo CE mode)
• bracelets, glasses, earphones, microSD cards, SD cards – for pairing, secure access, flash memory locking

Video NFC Communication distance of 9mm antenna in PLM

Video Micro Coil NFC Antenna in Feature Phones

Video Micro Coil NFC Antenna in Metal Objects

• reduced size occupying approximately 80% -90% less area than conventional antennas with similar performance
• great performance as it works stably and it transfer signals in all directions even in the presence of metallic materials which usually degrade the signal transmission quality of common antennas on the market
• saving effort required for NFC designs and as individual model modifications as it is not necessary to adjust the arrangement of metallic components near to the antenna
• reducing BOM by removing the ground plane and ferrite shielding
• easy mounting as it has electrodes at both ends, the antenna is capable of reflow soldering and surface mounting, and thus requires no additional pin connectors. Micro coil antenna can be picked from a tape and directly placed on PCB
• affordable price with reduced BOM, save up efforts on tuning, mounting and new design development for modified products this in total make the cost comparable with standard NFC antennas

The micro coil NFC antennas are tiny and it is not necessary to adjust the arrangement of metallic components near to them. Coil antennas are not much sensitive to the product’s casing. Coil antennas would limit steps needed to achieve matched and tuned NFC system and save effort for individual model modifications.
Because of its small size, multi-directional NFC performance and simple mounting – the micro coil NFC antenna can be placed in any part of the PCB
With the micro coil NFC antenna only general tuning for NFC controller is required; no additional tuning of individual product models needed

Unlike with planar NFC antennas ground plane and ferrite shielding are not needed.

The micro coil NFC antenna is SMT component that can be easily “picked & placed”. The coils are packed for delivery into reels.

With a few capacitors the micro coil NFC antenna can be tuned for the particular NFC controller. Coil antenna can be placed directly on PCB. As the coil antenna has electrodes at both ends, the antenna is capable of reflow soldering and surface mounting. It does not require additional pin connectors.

This makes assembly costs and effort lower compared to NFC antennas that are using external connectors or 3D structures.

The 9mm coil antennas are designed by Logomotion and produced in EU. The standard inductance tolerance in automated production is ±5%. On request, we can offer smaller inductance tolerance. For the samples, the tolerance is not guaranteed. Automated production of customized sizes of the coil antennas can be discussed for volume orders. 

Contact our expert team to design micro coil NFC antennas customized for your
future NFC enabled products.