ST25R3911B Antenna Response Distance and Impedance Matching Debugging

[J-luu]

This is a custom-made PCB antenna board utilising the ST25R3911B chip, but I am unsure how to proceed with impedance matching debugging and parameter configuration.

Could you offer some guidance? Below are the antenna dimensions, the calculated impedance matching values, and the original impedance matching diagram. Communication is currently possible at very close range.

To increase communication distance and stability, what modifications should be made?

*This post has been translated from Chinese to comply with the ST Community guidelines.

[Ulysses HERNIOSUS]

Hi,

please refer to AN4974: Antenna matching for ST25R3911B/ST25R391x devices. 

BR, Ulysses

[Travis Palmer]

Hi J-luu,

120nH antenna inductance seems very little for a 4 turn antenna with approx.. 30 to 40mm diameter.

Could you please share a smith chart of the antenna and antenna + matching network?

What is the read range you are able to achieve and what is your desired read range?

BR Travis

[J-luu]

目前使用的阻抗匹配网络如图1所示，意法半导体官方分析如图2所示。与图3相比，当前读数范围仅为5CM。要实现10CM左右的读取范围，我们该如何优化天线呢？或者你能提供正确的圆形天线吗？由于缺乏测量天线参数的设备，只能填写计算值进行阻抗匹配

[Berenice BENVEGUDA]

Hello @J-luu ,

the language to be used on this Community is English. Otherwise we cannot bring you any help.

Is your question correctly translated below : 

"The impedance matching network currently used is shown in Figure 1, and the official analysis by STMicroelectronics is shown in Figure 2. Compared to Figure 3, the current reading range is only 5cm. To achieve a reading range of about 10cm, how can we optimize the antenna? Or can you provide the correct circular antenna? Due to the lack of equipment to measure antenna parameters, we can only fill in the calculated values ​​for impedance matching."

Bets Regards

BB