确定距参考平面的物理偏移长度

对不起，我的意思是回波损耗必须接近0 dB。
不是40分贝。



     以下为原文

  Sorry I mean the return loss must be near to 0 dB. Not 40 dB.

> {quote：title = LabDevo写道：} {quote}>您好，>我阅读了以下在线文档，并对参考平面的物理偏移长度有疑问。
>> http://cp.literature.agilent.com/litweb/pdf/5989-4840EN.pdf >>我想设计同轴溶质校准标准，我不知道如何从参考定义物理偏移长度
飞机的短而开放。
我的频率范围从10 MHz到大约20 GHz，我希望在整个范围内平均回波损耗约为40 dB。
可以使用以下公式计算我的长度：确切的偏移长度并不重要。
最重要的是，开口和短路的偏移应该接近 - 理想情况下，短路的偏移距离比开放的稍长。
但除非你可以描述它们，否则它们将对你毫无用处。
表征它们并非易事。
尽管所有网页都告诉您如何制作自己的校准套件，但事实是它并不容易，特别是在20 GHz时。
我自己的公司生产低成本校准套件http://www.kirkbymicrowave.co.uk/但我们什么都不做，可以达到你要求的那种规格。
我不知道“平均”回报损失是什么用途。
大多数人希望在某些频率范围内出现最坏的情况，并且使用自制标准在20 GHz时不会达到40 dB。
人们需要滑动负载。
我刚检查了Keysight 85052B 3.5 mm校准套件的手册。
其中的负载在8到20 GHz之间具有至少36 dB的回波损耗，在20和26.5 GHz之间降至34 dB，因此即使是Keysight套件也不会为您提供40 dB回波损耗的固定负载。
说真的，如果你想在20 GHz下工作，而是来自Keysight，Rosenberger，Anritsu，Rohde＆amp; Sons的新型校准套件。
Schwarz或Maury微波炉。
如果您有HP / Agilent / Keysight VNA，那么从Keysight购买套件就更有意义了。
由于您的工作频率为20 GHz，我假设您使用的是3.5 mm。
85052D是适合该频率的价格合理的套件，85052B更好，因为它具有滑动负载。
您永远无法制作对20 GHz有用的套件。
戴夫



     以下为原文

  > {quote:title=LabDevo wrote:}{quote}
> Hello, 
> I read the following online document and have a question about the physical offset length from reference plane.
> 
> http://cp.literature.agilent.com/litweb/pdf/5989-4840EN.pdf
> 
> I want to engineering coaxial solt calibration standards and I don't have an idea how to define the physical offset length from reference plane of the short and open. My frequency span is from 10 MHz to about 20 GHz and I want an return loss of about 40 dB in average over the span. It is posibble to calculate my length with the following formula: 

The exact offset length is not critical. The main thing is that the offsets of the open and short should be close - ideally the short has a little longer offset distance than the open. But unless you can characterize them, then they are going to be useless to you. It is no trivial task to characterise them. 

Despite all the web pages that tell you how to make your own calibration kits, the truth is that it is not easy, and especially at 20 GHz. My own company produces low-cost calibration kits

http://www.kirkbymicrowave.co.uk/

but we do nothing that would achieve the sort of specifications you are asking for. I don't know what use an "average" return loss is to you. Most people want a worst case in some frequency range, and you are not going to achieve 40 dB at 20 GHz with home-made standards. One would need sliding loads for that. 

I just checked the manual for the Keysight 85052B 3.5 mm cal kit. The loads in there have a return loss of at least 36 dB between 8 and 20 GHz, falling to 34 dB between 20 and 26.5 GHz, so not even a Keysight kit will give you fixed loads with a 40 dB return loss.  

Seriously, if you want to work at 20 GHz, but a new cal kit from Keysight, Rosenberger, Anritsu, Rohde & Schwarz or Maury Microwave. If you have a HP/Agilent/Keysight VNA, then it makes far more sense to buy a kit from Keysight. 

Since you are working to 20 GHz, I assume you are using 3.5 mm. The 85052D is a reasonably priced kit for that frequency, and the 85052B is better, since it has sliding loads. 

You will never be able to make your own kit that is useful to 20 GHz. 

Dave

你好drkirkby，谢谢你的详细解答。
我们应该忘记20 GHz的旧规格，我还从键盘上阅读了一个套件手册。
：D让我们说最大值。
频率约为同轴标准的6 GHz，这样会更加真实。
我认为定义偏移非常困难，因为你找不到任何实际的描述如何去做。
例如，如何定义开放的偏移和边缘电容？
它是否只有很多经验和专业的模拟软件，如广告或cst？
我不知道如何开始它。
如果有人能给我一个方法或一些提示，那就太棒了。
对不起，我是这个主题的初学者，但每个人都从小开始。
：） 问候



     以下为原文

  Hello drkirkby,
thanks for your detailed answer.
We should forget the old specifications of 20 GHz , I also read a manual of a kit from keysight. :D

Let`s say the max. frequency is about 6 GHz of the coaxial standard, this would be more realistic. I think it is very difficult to define the offsets, because you can't find any practical description how to do it.
For example how to define the offsets and fringing capacitances of the open?
Is it only possible with a lot of experience and a professional simulations software like ads or cst?
I don't have any idea how to begin with it. It would be so great, if someone could give me a approach or some hints.
Sorry I am a beginner in this topic, but everyone starts small. :)

regards

（偏移延迟*光速）/（sqrt（空气的相对介电常数））=偏移长度（以米为单位）



     以下为原文

  (Offset delay*speed of light)/(sqrt(relative permittivity of air)) = offset length (in meters)

关于如何定义cal kit cal常量，有一些学术文章。
获取这些文件是第一个问题。
理解内容是第二个。
拥有设备是第三个。
1.用于毫米波矢量网络分析仪校准的同轴开路主要标准的表征和验证2.表征在毫米波频率下与同轴VNA一起使用的伪像标准3.通过物理测量表征校准标准4.使用校准标准表征
一家航空公司作为转让标准5.为Agilent 8510网络分析仪指定校准标准（Keysight P / N 5956-4352）我发现该列表中的第一个（＃1）是最全面和最丰富的。
在试图表征同轴开路时：使用空气测量系统和三维坐标测量机（CMM）来测量中心导体（a）和外导体（b）的直径。
激光位移测量系统（LDMS）用于测量中心导体（1）的偏移长度。
使用TRL校准套件校准的VNA用于在开放（Gamma）上产生S11数据。
这是您需要的所有数据（a，b，l，Gamma）。
根据这些数据，您可以使用公式来查找衰减常数（alpha），电阻率（p），特征阻抗（Z）和传播常数（y）。
然后，您可以使用此数据修改Gamma数据，以表示偏移结束时的Gamma，而不是配合平面上的Gamma。
使用这种新的Gamma数据，您可以获得同轴开路的正确相位数据。
您可以使用公式将频率相关的相位数据转换为频率相关的电容数据。
然后将这个与频率相关的电容数据放入一个程序中，该程序可以进行三阶多项式回归数据拟合，并获得令人垂涎的电容系数。
列出的第二个文件（＃2）有更多的见解。
不使用您没有的设备进行所有这些困难的测量，直径（a，b）根据IEEE标准简单地假定为标准尺寸。
和开路偏移的长度？
他们只是分开并测量长度！
此时，您拥有所需的所有机械尺寸（a，b，l）。
按上述步骤进行。
第三个文件（＃3）是最不实用的，但它至少告诉你一件事：使用Agilent HFSS软件，你可以插入机械尺寸，它将模拟一切并为你做所有的数学计算，给你
电容系数。
第四个文件（＃4）模糊地描述了确定电容系数的不同方法。
您使用TRL校准套件校准VNA。
然后在VNA端口放置一个长的无珠航空公司，然后将同轴开路连接到其末端。
得到的S11线性放大数据是纹波而不是您可能期望的开路直线。
这是揭示残余源匹配错误的已知方法。
此时，您应该调整/调整通用电容系数，直到获得最平坦的迹线，或者至少减小纹波的幅度。
如何做到这一点没有详细描述。
但是如果你能做到这一点，就意味着更好地校正剩余源匹配误差，因此优化了电容系数。
最后，文档＃5可以在因特网上获得。
第10页总结了计算电容系数的三种方法。
它们基本上都是一样的;
您使用VNA查找开路的S11数据。
技巧是补偿偏移长度。
该文件提出了其他文件所没有的内容;
使用时域门控来补偿偏移长度。
当然，该文档没有详细说明如何执行此操作。
但是，这种技术并不新鲜，你应该能够在那里找到信息。
时域通常是HP  Agilent  Keysight VNA的选项，因此如果您的VNA无法做到这一点，请不要感到惊讶。
这只是我读过的内容。
我最近才开始研究这些东西，所以我没有经验。
祝你好运。编辑：cmains于2016年4月4日上午12:26



     以下为原文

  There are a few scholarly articles on how to define cal kit cal constants. Getting access to these documents is the first hurtle. Understanding the content is the second. Having the equipment is the third.

1. Characterization and verification of coaxial open-circuit primary standards for millimeter-wave vector network analyzer calibration
2. Characterizing Artefact Standards for Use with Coaxial VNAs at Millimeter-wave frequencies
3. Characterization of Calibration Standards by Physical Measurements
4. Characterizing Calibration Standards Using one airline as a transfer standard
5. Specifying Calibration Standards for the Agilent 8510 Network Analyzer (Keysight P/N 5956-4352)

I found the first one on that list (#1) to be the most thorough and informative. In attempting to characterize a coaxial open-circuit:
An Air Gauging Measurement System and a three-dimensional Coordinate Measuring Machine (CMM) are used to measure the diameter of the center conductor (a) and outer conductor (b). A Laser Displacement Measurement System (LDMS) is used to measure offset length of center conductor (l). A VNA calibrated using a TRL cal kit is used to produce S11 data on the open (Gamma). This is all the data you need (a, b, l, Gamma). From this data, you use formulas to find the attenuation constant (alpha), resistivity (p), characteristic impedance (Z), and propagation constant (y). You then use this data to modify the Gamma data to represent Gamma at the end of the offset instead of Gamma at the mating plane. With this new Gamma data, you have have the correct phase data for the coaxial open-circuit. You use a formula to convert frequency dependent phase data into frequency dependent capacitance data. Then you put this frequency dependent capacitance data into a program that can do a third order polynomial regression data fit and you get the coveted capacitance coefficients.

The second document listed (#2) has some more insight. Instead of making all these difficult measurements using equipment you don't have, the diameters (a, b), are simply assumed to be standard dimensions according to the IEEE standard. And the length of the open-circuit offset? They just take it apart and measured the length! At this point you have all the mechanical dimensions you need (a, b, l). Proceed as mentioned above.

The third document (#3), is the least useful, but it at least tells you one thing: with Agilent HFSS software, you can plug in the mechanical dimensions and it will simulate everything and do all the math for you, giving you the capacitance coefficients.

The fourth document (#4) vaguely describes a different method to determining the capacitance coefficients. You calibrate a VNA using a TRL cal kit. Then you place a long beadless airline on the VNA port, and then connect the coaxial open-circuit to the end of that. The resulting S11 linear magnutide data is a ripple instead of the straight line you might expect from an open-circuit. This is a known method of revealing residual source match error. At this point you are supposed to adjust/tweak the generic capacitance coefficients until you get the flattest trace you can get, or at least reduce the amplitude of the ripple. How this is done is not described in detail. but if you could do it, it would mean the residual source match error is being better corrected and therefore the capacitance coefficients are being optimized.

Lastly, document #5 is readily available on the Internet. Page 10 summarizes three methods to compute the capacitance coefficients. They are all fundamentally the same; you use a VNA to find the S11 data for the open-circuit. The trick is compensating for the offset length. This document brings up something none of the other documents do; using time-domain gating to compensate for the offset length. Of course, the document doesn't go into detail on how to do this. However, this technique is nothing new and you should be able to find information out there. Time domain is usually an option for HPAgilentKeysight VNAs, so don't be surprised if your VNA can't do it.

This is only from what I've read. I've only recently started researching this stuff, so i have no hands on experience. 
Good luck.

Edited by: cmains on Apr 4, 2016 12:26 AM