怎么测试电缆的VNA校准程序

您是使用这条电缆作为其他设备（如PCB）的测试接口，还是您要测试的东西。
如果您要将其连接到其他东西，那么可能usinig自动端口扩展是最简单和最好的方法。
您可以通过查看PNA中的帮助文件或在Agilent支持网站上在线查找。



     以下为原文

  Are you using this piece of cable as a test interface to another devices (like a PCB) or is it the thing that you want to test.

If you are going to connect it to something else, then probably usinig automatic port extension is the simplest and best method.  You can find it by looking in the help file in the PNA or online at the Agilent support site.

嗨，安捷伦技术团队，我对使用端口扩展进行校准有疑问。
我做了一个1端口非制导反射校准。
使用该校准集，史密斯图表上的s11读数为0.775 - j 424欧姆，连接开放标准。
然后我需要将3英寸长的同轴电缆连接到系统，所以我在Dist中添加了3英寸的手动端​​口扩展。
启用端口扩展后，史密斯图表上的s11读取为2.63 - j 7.52欧姆，连接开放标准。
我的问题是，当启用端口扩展时添​​加3英寸电缆时，s11读数应该与原始calset相同。
感谢您的帮助！
面包车



     以下为原文

  Hi Agilent Technical Team,

I have a question regarding about calibration using Port Extension. I've done a 1-port Unguided reflection calibration. With that calset, the s11 reading on the smith chart is 0.775 - j 424 ohms with the open standard connected. And then I need to connect a 3 inches long coax cable to the system, so I did a manual port extension by adding 3 inches in the Dist. After I enabled the port extension, the s11 reads on the smith chart is 2.63 - j 7.52 ohms with the open standard connected. My question is that the s11 reading supposed to be the same as the original calset, when the 3 inches cable was added with the port extension enabled.

Thank you for your help!

Van

仅当速度因子为1时，3英寸才是物理长度。
典型的电缆的速度系数为.7，因此3英寸电缆的电气长度为3 /（0.7）或接近4.3英寸。
要正确设置扩展，您必须知道电缆的速度因子。
如果您测量打开（尝试将标记格式转换为日志/阶段，则更容易解释，在标记....对话框下）并查看值，然后添加电缆，添加适当的端口扩展，测量再次打开
它应该读取几乎相同的值，除了不匹配效应，对于短的，匹配良好的电缆应该很小。



     以下为原文

  3 inches is the physical length only if the velocity factor is one.  A typical cable will have a velocity factor of .7, so a 3 inch cable will have an electrical length of 3/(0.7) or almost 4.3 inches.  To set the extension properly, you must know the velocity factor of the cable.

If you measure the open (try chaning the marker formate to log/phase, it's easier to interpret, under the marker.... dialog) and see a value, then add a cable, add the proper port extension the measure the open again, it should read nearly the same value, except for mismatch effects, which should be small for a short, well matched cable.