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[问答]

设备上有一个非常明显的波纹

I 1)在我的8720D VNA的3.5 mm测试电缆上卡住了几个3.5 mm到N的适配器。
一个给了我一个女性N,另一个给了一个男性2)用一个85032B校准套件从50 MHz到6 GHz进行了VNA的完整2端口校准。
我没有使用平均值,但确实将IF带宽从默认的3 kHz降低到1 kHz。
3)及时测量额定为1 GHz的衰减器的S21。结果如图所示。
我知道S11和S12在6 GHz时大约为20 dB,但这个衰减器的额定值不是1 GHz。
设备上有一个非常明显的波纹,这可能是真实的,但可能不是。
这种纹波的频率是否表明有用?
这是过度的还是预期的?
戴夫

以上来自于谷歌翻译


     以下为原文

  I  

1 ) Stuck a couple of 3.5 mm to N adapters on the 3.5 mm test cables of my 8720D VNA. One gave me a female N, the other a male  
2) Performed a full 2-port calibration of the VNA from 50 MHz to 6 GHz with an 85032B cal kit. I used no averaging, but did reduce the IF bandwidth to 1 kHz from the default 3 kHz.
3) Promptly measured S21 of an attenuator rated to 1 GHz.surprising  

The result is as shown. I know that S11 and S12 are of the order of 20 dB at 6 GHz, which is not given this attenuator is rated to 1 GHz.

There is a very noticable rippled on the device, which may be real, but may be not. Does the frequency of this ripple indicate anything useful? Is this excessive, or to be expected?

Dave   
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孔德羲

2019-2-26 11:29:50
除非您的衰减器大约超过1米,否则纹波看起来是来自校准残差。
最有可能在传输跟踪项中(因为衰减器的匹配将消除源和负载匹配残差的影响。纹波水平(+ -0.02 dB)几乎是可预测的,假设残差为-58 dB
匹配(源或负载)和原始匹配。因此,具有15 dB源和负载匹配以及43 dB残余源和负载匹配的系统将产生这样的响应。

以上来自于谷歌翻译


     以下为原文

  Unless your attenuator is on the order of more than 1 meter long, the ripple looks to be from calibration residuals. Most likely in the transmission tracking term (as the match of the attenuator will eliminate the effects of source and load match residuals.

The level of the ripple (+-0.02 dB) is nearly exaclty what would be predicted given -58 dB product of residual match (source or load) and raw match.    Thus, a system with 15 dB source and load match and a 43 dB residual source and load match would produce such a response.
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李青

2019-2-26 11:38:52
引用: 脑洞大赛9 发表于 2019-2-26 11:29
除非您的衰减器大约超过1米,否则纹波看起来是来自校准残差。
最有可能在传输跟踪项中(因为衰减器的匹配将消除源和负载匹配残差的影响。纹波水平(+ -0.02 dB)几乎是可预测的,假设残差为-58 dB
匹配(源或负载)和原始匹配。因此,具有15 dB源和负载匹配以及43 dB残余源和负载匹配的系统将产生这样的响应。

> {quote:title = Dr_joel写道:} {quote}>除非您的衰减器大约超过1米,否则纹波看起来来自校准残差。
最有可能在传输跟踪项中(因为衰减器的匹配将消除源和负载匹配残差的影响。>>纹波电平(+ -0.02 dB)几乎是可以预测的-58 dB产品
剩余匹配(源或负载)和原始匹配。因此,具有15 dB源和负载匹配以及43 dB残余源和负载匹配的系统将产生这样的响应。谢谢Joel,衰减器是典型的长度。
N衰减器(即那些波纹是否过量,因为我有* 8720D *正确的安捷伦测试电缆* 3.5 mm到N型适配器来自安捷伦校准套件* 85032B校准套件?如果有人告诉你,你会告诉他们去吗?
正确地校准他们的VNA,或者你认为可以接受吗?可以合理地期望用更好的VNA和带有滑动负载的校准套件做得更好吗?我有一个85055A验证套件,但不确定我是否可以使用它
85032B cal kit,所以真的没有任何办法
看看我的校准是否是可接受的。
DaveEdited:drkirkby于2013年4月21日下午2:18

以上来自于谷歌翻译


     以下为原文

  > {quote:title=Dr_joel wrote:}{quote}
> Unless your attenuator is on the order of more than 1 meter long, the ripple looks to be from calibration residuals. Most likely in the transmission tracking term (as the match of the attenuator will eliminate the effects of source and load match residuals.

> The level of the ripple (+-0.02 dB) is nearly exaclty what would be predicted given -58 dB product of residual match (source or load) and raw match.    Thus, a system with 15 dB source and load match and a 43 dB residual source and load match would produce such a response.

Thank you Joel,

The attenuator was a typical length for an N attenuator (i.e. << 1 m long), so we can assume it is calibration residules. 

Are those ripples excessive given the kit I have

*  8720D
* The correct Agilent test cables
* 3.5 mm to N adapters from an Agilent calibration kit
* 85032B cal kit



If someone showed you that, would you tell them to go and calibrate their VNA properly, or would you think that acceptable? 

Could one reasonably expect to do better with a better VNA and cal kit with sliding loads? 

I've got an 85055A verification kit, but are not sure if I can use it with my 85032B cal kit, so don't really have any way of seeing if my calibration is acceptabel or not. 

Dave

Edited by: drkirkby on Apr 21, 2013 2:18 PM
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孔德羲

2019-2-26 11:53:49
它处于良好校准的极限。
比我在低端预期的纹波更多,但它实际上看起来更残留波纹的噪声。
扫描是步进还是扫描模式(看起来像扫描模式给我)?
在扫描模式下,由于IF延迟,可能会出现一些涟漪。
此外,纹波图案是固定还是扫描到扫描?
如果你摆动dut和电缆,它是稳定的还是变化的?
我猜可怜的电缆是造成这种影响的最可能原因。

以上来自于谷歌翻译


     以下为原文

  It is at the limit for a good calibration.  More ripple than I would expect at the low end, but it actually looks more noiselike that residual ripple.

Is the sweep in stepped or swept mode (it looks like swept mode to me)?  In swept mode, some ripples can show up because of IF delay.

Also, is the ripple pattern fixed or does it vary sweep to sweep?  If you wiggle the dut and cables, is it stable or does it change?  I would guess poor cables to be the most likely cause of this effect.
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