怎么使用端口扩展进行校准

> {quote：title = Van H写道：} {quote}>嗨，安捷伦技术支持团队，>>我有一个关于使用端口扩展进行校准的问题。
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。
>>谢谢你的帮助！
范我很惭愧地说我没有使用端口扩展，但我对它做的事情有一个粗略的想法。
（我不确定我的8720D是否真的支持它们）。
请记住，在测量像S12或S21这样的传输时，3英寸的延迟将导致延迟X ps。
但是相同的3英寸将在S11或S22等反射信号上产生两倍的延迟。
看看将端口扩展到您认为需要的一半的效果。
我认为对VNA的一些修正将这种差异考虑在内。
它可能是Port Extensions，而Offset Delay则没有。
我需要查看Joel的书，以确定Port Extensions确实如此，但我希望这将在用户手册中。
我希望这是一些帮助，但正如我所说，我不是这方面的专家。
戴夫



     以下为原文

  > {quote:title=Van H wrote:}{quote}
> Hi Agilent Technical Support 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
 
I'm ashamed to say I have not used port extensions, but I have a rough idea the sort of thing it does. (I'm not sure if my 8720D actually supports them). 

Bear in mind that when measuring a transmission like S12 or S21, a delay of 3 inches will cause a delay X ps. But the same 3 inches will cause twice that delay on a reflected signal like S11 or S22.

Look at the effect of extending ports by half of what you think you need. I think some corrections on VNAs take this difference into account. It might be Port Extensions does, and Offset Delay does not. 

I wold need to look at Joel's book to be sure exactly Port Extensions does, though I expect this would be in the user manual. 

I hope this is some help, but as I say, I am no expert on this. 

Dave

正如我所说，我没有使用端口扩展，但更多地考虑它，如果你使用同轴电缆并增加76毫米（3英寸），那么电气你会增加更长的长度，这取决于电缆的速度因素。
典型地，速度因子是0.67，所以电气上你会增加76 / 0.67 = 113 mm。端口扩展上可能有一个选项来指定速度因子。如果不是，你将需要计算出电气长度
亲自动手。戴夫



     以下为原文

  As I say, I have not used port extensions, but thinking about it more, if you use coax and add 76 mm (3"), then electrically you would have added a longer length, which depends on the velocity factor of the cable. Typiclly the velocity factor is 0.67, so electrically you would have added 76/0.67 = 113 mm. 

There might well be an option on the port extensions to specify a velocity factor. If not, you are going to need to work out the electrical length manually. 

Dave