E4980A带16451B电介质常数随间隙增加

我有一个带有16451B附件的E4980A LCR仪表，用于测试材料的介电常数。
我用它来表征一些聚合物，但是通过简单地测量空气的介电常数来进行一些理智检查，只是为了确认一切都井然有序。
然而，我发现我得到了意想不到的结果。
基本上，对于所有间隙，介电常数应该是常数1，但测量值告诉我它随间隙增加。
这在附图中显示。
关于要看的事情的任何建议？
我执行了一个简短的修正，但这只是一个偏移。
我有点困惑，因为如果它只是一个偏移，那不是一个大问题，但我担心的是，测量结果告诉我空气的介电常数会随着间隙而变化。
我仔细阅读了手册，看到第3-61页有一张表可以用来进行区域校正，但与我看到的问题相比，这种校正相对较小。
我很感激任何建议。



     以下为原文

  I have a E4980A LCR meter with a 16451B attachment for testing the dielectric constant of materials. I am using it to characterize some polymers, but have performed some sanity-check by simply measuring the permittivity of air, just to confirm everything is in order. I am finding, however, that I am getting unexpected results. Basically, the permittivity should be a constant 1 for all gaps, but the measurements are telling me that it increases with gap. This is shown in the attached plot.  

Any suggestions on things to look at? I perform a short correction, but this is just an offset. I'm a little perplexed because if it were simply an offset, that isn't as big a concern, but I am concerned by the fact that the measurements tell me the permittivity of air would be changing with gap. I've looked through the manual and see that there is a table on page 3-61 that can be used to make area corrections, but this correction is relatively small compared to the issue I am seeing.

I appreciate any suggestions.   
附件

• figure.png4.5 KB