为什么当RF禁用时M24SR天线的行为会类似于短路变压器

大家好。我目前的项目需要使用NFC和RFID接口。我使用ST M24SR与NFC供电的智能手机进行交互，使用NXP PN532读取13.56 MHz卡和内部设计的电路，用于读取125 kHz em-marine卡。所以我有三个天线放在另一个里面。我将这些IC中的每一个短时间转动以扫描适当的标签或电话。如果我同时转动其中两个发生碰撞并发生奇怪的行为。
当M24SR天线位于其他地方时，一切似乎都没问题。但是当我根据设备设计要求将所有天线放在一起时，我会观察到以下行为：当我使用RF禁用禁用M24SR上的RF前端时，引脚AC0和AC1表现得像一个短路，对其他天线来说是非常重的负载。因此，当激活M24SR能够与智能手机进行交互时，我的设备的所有其他部分都无法正常工作。我正考虑将RF开关与AC0引脚串联。我不熟悉天线匹配等所有RF技巧，我不确定RF开关的耐用性（在我的设计中它应该每两秒切换一次，设备应该全天候工作），所以我问你们，如果有人有更好的想法。

#collision #antenna #nfc＃m24sr



以下为原文




Hello everyone. My current project requires working with NFC and RFID interfaces. I use ST M24SR to interact with NFC-powered smartphones, NXP PN532 to read 13.56 MHz cards and inhouse-designed circuitry for reading 125 kHz em-marine cards. So I have three antennas put one inside another. I turn each of these ICs for short moment of time to scan for appropriate tags or phones. If I turn two of them simultaneously collision occurs and weird behavior happen.
When M24SR antenna is situated aside others everything seems to be OK. But when I put all antennas together as required by device design I observe following behavior: when I disable RF frontend on M24SR using RF disable, pins AC0 and AC1 behave like a short circuit and act as pretty heavy load for other antennas. So, when activated M24SR is able to interact with smartphone, but all other parts of my device cant properly work. I was thinking about putting RF switch in series with AC0 pin. I am not familiar with all that RF tricks like antenna matching and I am not sure on RF switch endurance (in my design it should switch every two seconds and device should work 24/7), so I am asking you guys, if anyone have better ideas.

#collision #antenna #nfc #m24sr