VNA规范一般问题理解

> {quote：title = SOLT_guy写道：} {quote}>这是一个关于理解VNA规范的一般性问题。
>>我拥有8753C（但我必须使用其他网络分析仪完成我的工作），我必须与客户和管理层就网络分析仪测量的准确性进行对应。
因此，我的回复必须准确并且不能“一般”正确，因为这些测量可能与校准实验室测试或具有严格标准的一些其他应用相关联。
>>>如果我看一下“相位特性” - 频率响应偏离线性部分的接收机仪器规格，从300KHz到3 GHz有一个规格+或负3度。
根据这个规范。
我看到了一个图表。
>如果我回忆正确，这是原始测量。
因此，与校准测量得到的结果无关>我需要根据实际相角测量的正式断言来解释该图。
>>从图中可以看出，6 GHz时线性偏离2度（参见用户手册第19-873C仪器规格部分），3 GHz时偏差约1度。
>>让我们说我运行了性能测试，我的性能测试数据输出与图表完全相同。
>>>我能告诉想知道相位测量精度的客户，我的相位测量值在6 GHz±2度和3 GHz一度（测试数据）吗？
>您必须添加测试方法的不确定性或错误。
>或者我只能说安捷伦在正负3度指定其NA相位测量值（也就是说，如果“线性相位特性”的这种解释等同于相位测量的相位角“精度”测量）。
>同样，这是未经纠正的反应。
>术语“线性相位特征”是否等于相位角“精度”测量值？
>不，它正是它所说的：它是与线性相位的偏差。
但相位精度应包括线性相位效应。
在测试集端口添加一段线路将不会明显改变线性相位的偏差（它将基本上只有线性相位，即直接随频率变化的相位），但肯定会改变绝对相位数。
>请帮我准确定义这些规范的真正含义。
>>感谢您过去的回复。
>>编辑：SOLT_guy于2012年5月21日上午4:11 >>编辑：SOLT_guy于2012年5月21日上午4:13 >>编辑：SOLT_guy于2012年5月21日下午3:54 >>编辑：
SOLT_guy于2012年5月21日下午3:57 >>编辑：SOLT_guy于2012年5月30日上午1:07



     以下为原文

  > {quote:title=SOLT_guy wrote:}{quote}
> This is a general question about understanding VNA specs.
> 
> I own a 8753C (but I have to use other network analyzers for my job) and I have to correspond with customers and management with respect to the accuracy of the network analyzer measurements.    Therefore, my replies have to be exact and cannot be "generally" correct because these measurements may be associated with calibration laboratory tests or some other application with exacting standards.
> 
> If I look at the receiver instrument specifications under the section, "Phase Characteristics" - Frequency Response Deviation from Linear, there is a spec + or minus 3 degrees from 300KHz to 3 GHz.   Under this spec.  I see a graph.
> 
If I recollect correctly, this is for raw measurements.  So it is unrelated to the results you get with calibrated measurements
> I need to interpret this graph with regard to what can be formally asserted with respect to actual phase angle measurements.
> 
> From the graph I can see that there is a 2 degree deviation from linear at 6 GHz (see page 19 - 8753C  instrument specifications section of the user manual) and about one degree deviation at 3 GHz.  
> 
> Let's say I ran a performance test and my performance test data output was exactly the same as the graph.
> 
> Can I tell a customer who wants to know the accuracy of my phase measurements that my phase measurement is within plus or minus 2 degrees at 6 GHz and one degree at 3 GHz (data from a test)?
>
You must add the uncertainty or error of the test method. 
> Or am I only entitled to say that Agilent specifies its NA phase measurements at plus or minus 3 degrees (that is, if this interpretation of "linear phase characteristics" is equivalent to the phase angle "accuracy" measure of a phase measurement).
>
Again, this is uncorrected response. 
> Is the term "linear phase characteristics" equivalent to the phase angle "accuracy" measure?
> 
No, it is exactly what it says: it is the deviation from linear phase.   But phase accuracy should include the linear phase effects.  Adding a length of line to your test set port will not appreciable change the deviation from linear phase (it will and substantially only linear phase, that is phase that changes directly with frequency), but will certainly change the absolute phase number.
> Please help me define exactly what these specifications are really saying.
> 
> Thank you for your past replies.
> 
> Edited by: SOLT_guy on May 21, 2012 4:11 AM
> 
> Edited by: SOLT_guy on May 21, 2012 4:13 AM
> 
> Edited by: SOLT_guy on May 21, 2012 3:54 PM
> 
> Edited by: SOLT_guy on May 21, 2012 3:57 PM
> 
> Edited by: SOLT_guy on May 30, 2012 1:07 AM

亲爱的Dunsmore博士;
谢谢你的回复，这是最具启发性的。
关于相位角精度的测量，我读了一篇两页的文章（由Bird公司出版），标题为“VSWR：电压直立率”。
文章在第2页，第二段说：“开槽线仍然是最准确的仪器，产生VSWR和相角信息”我上传了文章，以便您可以验证其真实性。
这篇文章似乎没有过时。
我的问题是，是否有一项独立的研究报告证实现代网络分析仪比开槽线更准确地进行相位测量？
我意识到每个特定单元的“工艺”可能决定了它的实际测量精度，但我指的是一个一般情况，即被测单元是由制造商和型号识别的随机样本（“现成的”）
。
我知道进行了一项独立研究，比较了专用TDR单元与NA TDR单元，并暗示NA TDR单元在特定条件下输出的数据测量不确定性低于专用TDR单元（“使用VNA和TDR测量不确定度的比较
同轴电缆，“由Paul Pino，WL Gore＆amp; Associates Inc.，Landenberg，PA - Cables＆amp; Connectors 2010 A Microwave Supplement to Microwave Journal）。
是否有研究表明，与使用相对现代的网络分析仪进行相角测量相比，开槽线相位角精度测量结果相比较？编辑：SOLT_guy于2012年6月3日上午9:36



     以下为原文

  Dear Dr. Dunsmore;

      Thank you for your reply, it was most enlightening.   

       With regard to the measurement of phase angle accuracy, I read a two page article (published by Bird corporation), entitled, "VSWR: Voltage Standing Ratio."   The article says on page 2, second paragraph down:

"The slotted line is still the most accurate instrument, yielding both VSWR and phase angle information"

       I have uploaded the article so that you may verify its authenticity.   The article does not appear to be dated.   

       My question is, was an independent study ever published which verified that the modern network analyzer makes more accurate phase measurements than the slotted line?    I realize that the "workmanship" of each particular unit  may determine its actual measurement accuracy, but I am referring to a general case whereby the units under test are random samples ("off the shelf") that are identified by the manufacturer and model number.

       I know that an independent study was conducted comparing dedicated TDR units vs. NA TDR units and it was implied that the NA TDR units output less uncertainty in their data measurements than dedicated TDR units under specific conditions ("Comparision of VNA and TDR Measurement Uncertainty Using Coaxial Cables," by Paul Pino, W.L. Gore & Associates Inc., Landenberg, PA - Cables & Connectors 2010 A Special Supplement to  Microwave Journal). 

        Was a study ever presented that compared slotted line phase angle accuracy measurements as compared to the phase angle measurements using a, relatively, modern network analyzer?

Edited by: SOLT_guy on Jun 3, 2012 9:36 AM

附件

• Bird Article.pdf759.4 KB
  

我不知道有关开槽线精度的任何研究。
自从现代纠错技术的发明以来，我怀疑是否有人认真地使用开槽线作为测量超过30年。
开槽线有许多可以容易出错的区域，包括沿线的探针变化和探测器问题，我认为这些区域很难分析并创建误差范围。



     以下为原文

  I do not know of any study of the accuracy of slotted lines.  I doubt that anyone has seriously used slotted lines as measurements for more than 30 years, since the invention of modern error correction techniques.  Slotted lines have many areas that are open to error including probe variation along the line and detector issues, which I would suppose are very difficult to analyze and create error bounds for.

亲爱的Dunsmore博士;
非常感谢您的反馈。
我倾向于同意您对探头，探测器和其他模拟性设备可能产生的错误的潜在可能性的看法。
但是，我确实认为过于依赖数字化的数据解释有其缺陷。
模拟设备可能不完全准确，但它们作为“球场”数字的输出非常可靠。
我希望有人可能想为我们的讨论做出贡献。
我确实认为必须在某个时间进行比较，遗憾的是，其结论可能只与其发表的时间框架相关。
当网络分析仪处于发展阶段时，可能存在时间范围，而“时隙线”可能是“成熟”技术。
我仍然希望阅读有关这两种测量设备的文章或研究结果。
再次感谢您的反馈，希望有人能为此次讨论做出贡献。



     以下为原文

  Dear Dr. Dunsmore;

       Thank you very much for your feedback.  

        I would tend to agree with your opinions regarding the inherent potential for errors which may arise from probes, detectors, and other devices of an analog nature.   But, I do believe that becoming too dependent upon digitized interpretations of data has its pitfalls.   Analog devices may not be perfectly accurate but their output as a "ballpark" figure is very reliable.  

      I was hoping that someone out there may want to contribute to our discussion.   

      I do believe a comparision had to have been done at some time, unfortunately, its conclusions may only be relevant for the time frame that it was published.   

     It is probable that a time frame existed when the network analyzer was in its developmental stage while the "slotted line" was probably a "mature" technology.   I would still like to read the findings of the article, or the study, with regard to these two measurement devices.   

      Again, thank you for your feedback and, hopefully, someone will contribute to this discussion.