| 摘要 |
A system for detecting the depth of an antenna embedded in the card body of a smart card includes a milling device for forming a cavity in the card body, a test device disposed in close proximity to the card body, a vector network analyzer (VNA) for measuring a linear characteristic of the test device, and a control device for regulating operation of the milling device in view of data collected by the VNA. In use, the VNA generates a test signal and measures the degree of signal reflection from the test device. Under normal conditions, the VNA observes a spike in forward return loss at the natural resonant frequency of the open antenna circuit. However, at the instant that the milling device contacts the antenna, a notable variance in the degree of signal reflection is observed which indicates that the proper antenna depth has been reached. |
