同轴TRL校准反射/短平面必须非常接近吗

一般来说，是的，这是最简单的方法。
通常开放是一个很好的选择，除非辐射导致问题。



     以下为原文

  In general, yes, that is the simplest way.  Often an open is a good choice, unless radiation causes a problem.

我想为同轴TRL校准套件，Short更好，不是吗？
这是因为它对边缘影响较小。
这是正确的理解吗？



     以下为原文

  I thought for coax TRL calibration kit, Short is better, isn't it? This is because it has less fringing impact. 

is this the correct understanding?

实际上，TRL中的边缘电容根本不重要，只要它在端口1和端口2上是相同的。但是这假设它们没有辐射（如果两个端口上的绝对恒定，则辐射无关紧要）
。
但是对于PCB标准，开放通常在感兴趣的频带中辐射，并且相邻结构导致端口1和端口2的辐射不同，因此在这种情况下，短路更好。



     以下为原文

  In fact, the fringing capacitance in TRL doesn't matter at all, provided it is identical on port 1 and port 2.  But that presumes their is no radiation (which radiation doesn't matter either if it is absolutely constant on both ports). 

But for PCB standards, the open often radiates in the band of interest and adjacent structures cause the radiation to be different for port 1 and port 2, and so in such cases a short is better.

所以对我来说，只要两个端口看到相同的边缘电容和相同的辐射，通过使用open作为Reflect就不会有任何影响。
这是正确的理解吗？



     以下为原文

  so it sounds to me that as long as the two ports seeing the same fringing capacitance and the same radiation, it would affect nothing by using open as the Reflect.

is this the correct understanding?

TRL校准的反射标准有两个要求。
1）端口1和端口2反映标准相同。
2）反射标准的相位需要在每个频率点的+/- 90度内知道。
这意味着反射标准的偏移延迟值需要在最高频率点的1/4波精度内定义。
如果你可以在参考平面上制造短路，你的延迟是零，应该可以正常工作。
否则，您需要对延迟值进行良好估计，延迟值是参考平面与短路位置之间的偏移长度的函数。
打开的电容会导致相位随频率的变化而变化，必须适当考虑。
辐射或耦合到另一个端口是额外的问题。



     以下为原文

  There are two requirements for the reflect standard for TRL calibration.  1) Port 1 and Port 2 reflect standards are equal. 2) The phase of the reflect standards need to be known within +/- 90 degrees at every frequency point.  That implies that the offset delay value of the reflect standards needs to be defined within a 1/4 wave accuracy at the highlest frequency point.  If you can fabricate shorts right at the reference planes, your delay is zero and should work ok. Otherwise, you need a good estimate of the delay value, a function of the offset length between your reference planes and the location of the shorts.  Fringing capacitance of the the open can cause phase to change as a function of frequency and must be accounted for properly.  Radiation or coupling to the other port are addtional concerns.

谢谢。
你是什​​么意思，_否则，你需要一个很好的延迟值估计，一个函数的参考平面之间的偏移长度和shorts._的位置的同轴电缆，有时很难在参考时做短
平面。
当你说参考平面和短路的偏差之间的偏移长度的函数时，你有一个考试吗？
所以我知道如何实现这一点。



     以下为原文

  thanks. 

what do you mean by,

_Otherwise, you need a good estimate of the delay value, a function of the offset length between your reference planes and the location of the shorts._ 

for coax, sometimes it is difficult to make the short at the reference plane. when you say a function of the offset length between the refernce plane and the loacation of the short, do you have an examle? so i know how to implement this.