Figure 4 shows the coil former of the sample antenna.
Antenna inductance ≈ 440 µH
Coil = 66 turns
Wire = enameled copper wire
Wire diameter = 0.18 mm
The antenna is designed for a free-air application. Connect a parallel resistor of 15 kΩ to the antenna to reduce the quality factor. If the antenna is mounted on a keylock, the antenna parameters must be redefined.