4 Antenna Design

The antenna coil inductance is measured at 1.84 µH as shown in Figure 7. To calculate the parallel tuning capacitors required, the resonant frequency formula in Equation 1 should be used. For further details on antenna tuning, see the RF430CL330H Practical Antenna Design Guide (SLOA197).

Figure 8 shows the measured resonant frequency at 13.66 MHz with 274.3 kHz. This results in a Q factor of less than 50 using the calculation shown in Equation 2. The read range of this reference board is 8cm using the TRF7970AEVM reader.