Failure of blind via is one of the main causes of an open circuit in printed circuit board(PCB).

盲孔开裂是导致印制电路板（PCB）电气断路的主要原因之一。

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By connecting coax cables to all four output ports as shown, an open-circuit calibration can be performed.

如图所示，通过将同轴电缆连接之所有的4个输出端口，则可进行开路校准。

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