完善资料让更多小伙伴认识你,还能领取20积分哦, 立即完善>
对Ken Wong来说可能更多,但欢迎任何有知识的人回答。
我对使用开放式N连接器作为SOLT校准的校准标准感兴趣。 我知道它不会像真正的开路标准那样准确,但显然可能 - FieldFox系列的“Quickcal”就是这样做的。 我早就认为HFSS可能是一种解决这个问题的方法,并找到了Ken Wong的论文K.H. Wong,“通过物理测量对校准标准进行表征”,第69届ARFTG会议摘要,1992年6月,我发现非常有趣。 Ken使用HFSS进行了非常精确的物理测量和计算机建模的组合 - 显然这早于安捷伦的EMpro,它与HFSS具有大致相似的功能。 Ken的论文中我不清楚的是,校准标准的数据是如何从HFSS模型中得出的。 我想做的是:1)设置一个开放的公N连接器的HFSS模型。 这将附加一些同轴电缆。 合理长度的同轴电缆距离N连接器的参考平面60 mm。 确切的长度不应该太重要,虽然人们不想太长时间,因为它只是浪费计算机资源,但人们也需要这些领域已经安定下来,所以我认为这也不是明智的做法 短。 我认为将同轴电缆变成一家航空公司是合理的 - 至少在最初阶段,这是第一次解决这个问题。 2)在同轴电缆的末端添加一个波形端口3)运行HFSS并让它确定波形的S参数,该参数距离N连接器的参考平面60 mm。 4)在HFSS中使用后处理在N连接器的参考平面上找到S参数。 不过,第4步对我来说是一个问题。 在HFSS中,可以在后处理中将参考值移动60 mm。 我这里没有HFSS的副本,但我知道可以做到。 因此原则上可以将模拟的参考平面移动到N连接器的参考平面,从而在参考平面上找到属性。 但我不认为参考平面的简单运动在这种情况下是有效的,因为我认为HFSS会假设传输线的横截面是均匀的。 但是N连接器不会 - 公引脚逐渐变细。 因此,我没有看到如何估计N连接器的参考平面上的S参数,这将是将其用作校准标准所需的。 很难确切地知道Ken如何使用HFSS,但我怀疑HFSS用于确定1.85,2.4和3.5 mm连接器参考平面的S参数。 我对如何做到感兴趣。 对我来说,用一些同轴电缆建模连接器并确定相位角似乎很容易。 如何使用该信息来找到参考平面上的边缘电容是不太明显的,我认为这是为了使用精确的物理测量和计算机模拟的组合来表征校准标准所需要的。 *关于计算机时代写的科学论文的一般评论。*当我在学校时,我们被告知在科学实验中以其他人可以重复它来验证结果的方式写下实验。 利用现代论文,利用计算机模型,基本上不可能以别人可以重现它的方式编写实验。 使用像HFSS这样的现代专有软件,这些软件将在几年内淘汰,运行在几年后也将过时的硬件上,这将使得其他任何人都无法重复这些结果。 最近我发现了一篇感兴趣的论文,其中有人使用Fortran并提出让他的代码可用。 我本来想得到这些代码,但是得出的结论是作者无法联系到,而且很可能已经死了。 这不是对肯的论文的批评 - 我自己的博士。 论文有计算机模拟,没有人可以复制。 戴夫 以上来自于谷歌翻译 以下为原文 This is probably more for Ken Wong, but anyone else with knowledge is welcome to answer. I'm interested in using an open N connector as a calibration standard for a SOLT calibration. I know it will not be as accurate as a true open circuit standard, but it is clearly possible - the "Quickcal" on the FieldFox range do this. I've long since thought HFSS may be a way to tackle this, and found Ken Wong's paper K.H. Wong, “Characterization of Calibration Standards by Physical Measurements,” 39th ARFTG Conference Digest, June 1992 which I found very interesting. Ken used a combination of very accurate physical measurements and computer modelling using HFSS - obviously this pre-dates Agilent's EMpro, which has broadly similar capabilities to HFSS. What it is not clear to me from Ken's paper is how the data about the calibration standard is derived from the HFSS model. What I was thinking of doing, is: 1) Set up an HFSS model of an open male N connector. This would have some coax attached. A reasonable length of coax would be 60 mm from the reference plane of the N connector. The exact length should not matter too much, although one would not want to make it too long as it just wastes computer resources, but one also needs the fields to have settled down, so I don't think it is sensible to make it too short. I think it would be reasonable to make the coax an airline - at least initially anyway, as a first go at this problem. 2) Add a waveport at on the end of the coax 3) Run HFSS and let it determine the S-parameters at the waveport, which would be 60 mm away from the reference plane of the N connector. 4) Use post-processing in HFSS to find the S-parameters at the reference plane of the N connector. Step 4 is a problem for me though. In HFSS, it is possible to move the reference by 60 mm in post processing. I don't have a copy of HFSS here, but I know one can do it. So in principle one could move the reference plane for the simulation up to the reference plane of the N connector, and so find the properties at the reference plane. But I don't think a simple movement of the reference plane would be valid in this case, as I think HFSS would assume the transmission line is uniform in cross section. But the N connector would not be - the male pin tapers. Hence I don't see how to estimate the S-parameters at the reference plane of the N connector, which would be needed to use it as a calibration standard. It's hard to tell exactly how Ken used HFSS from that paper, but I suspect HFSS was used to determine the S-parameters at the reference plane of 1.85, 2.4 and 3.5 mm connectors. I'm interested in how that was done. To me it seems quite easy to model a connector with a bit of coax and determine the phase angle. It is less obvious how one could use that information to find the fringing capacitance at the reference plane, which is what I think is needed in order to characterise a calibration standard using a combination of accurate physical measurements and computer simulations. *General comment on scientific papers written in the computer age.* When I was at school we were told in science experiments to write up the experiment in a way someone else could repeat it to verify the results. With modern papers, making use of computer models, it is basically impossible to write up an experiment in a way someone else could reproduce it. The use of modern propriety software like HFSS, which will be obsolete in a few years, running on hardware which will also be obsolete in a few years, will make it impossible for the results to be repeated by anyone else. Recently I found a paper of interest, where someone had used Fortran and offered to make his code available. I would have like to have got the code, but had concluded the author could not be contacted, and was quite possibly dead. This is not a criticism of Ken's paper - my own Ph.D. thesis has computer simulations which nobody could reproduce. Dave |
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尽管可以使用3-D E& M模拟器来模拟开口端连接器,但由于许多不明确的物理结构,其有用性受到限制。
例如,对于公连接器,公引脚的作用类似于天线。 raidation特性对联轴器螺母的位置和长度非常敏感。 凸针尖的形状没有很好地定义,但它对辐射特性具有一阶影响。 还观察到工作频率内的共振。 对于N型,公引脚部分屏蔽,但设置在外导体的配合平面后面。 此后退会创建任何变量集,例如步进阻抗变化。 如果连接器的尺寸可以很好地控制,则可以对其进行建模并在共振区域下方使用。 获得电气特性的更简单方法是使用感兴趣的连接器作为测试端口连接器进行精确的1端口校准。 在纠错ON的情况下,测量开放式连接器的响应。 这就是FieldFox连接器模型生成的方式。 我的论文涉及物理定义良好的校准标准的建模。 开放标准是屏蔽开口,带有支撑的中心导体和定义的偏移长度。 使用当今的3-D E& M模拟器可以很好地模拟边缘电容。 那时候,我不得不使用包括专有工具在内的仿真工具。 许多论文都是关于开放式电容主题,特别是开放式同轴线电介质探头。 Marcuvitz的波导手册,第4.16节涉及同轴线辐射到半无限空间。 这些型号更适用于开放式母头连接器。 肯 以上来自于谷歌翻译 以下为原文 Although it is possible to model an open end connector using 3-D E&M simulators, its usefulness is limited because of many ill defined physical structures. For the male connector for example, the male pin acts like an antenna. The raidation characteristics is highly sensitive to the coupling nut's position and length. The shape of the male pin tip is not well define and yet it has a first order impact on the radiation characteritics. Resonances within operating frequencies were also observed. For Type-N, the male pin is partially shielded but sets behind the outer conductor's mating plane. This set back creates any set of variables such as step impedance change. If the connector's dimensions are well control, it can be modeled and used below the resonance region. An easier way to obtain the electrical characteristics is to do an accurate 1-port calibration, using the connector of interest as the test port connector. With error correction ON, measured the response of the open ended connector. That was how the FieldFox connector model generated. My paper deal with modeling of calibration standards that are well defined physically. The open standards are shielded opens with a supported center conductor and with a defined offset length. The fringing capacitance can be modeled nicely using today's 3-D E&M simulators. Back then, I had to use a comination of simulation tools including proprietary ones. Many papers had been publushed on the open capacitance topic, specifically on open ended coaxial line dielectric probes. The Waveguide Handbook by Marcuvitz, section 4.16 deals with coaxial line radiating into semi-infinite space. These models are more applicable for open ended female connectors. Ken |
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60user22 发表于 2019-1-7 09:23 Hi Ken, thank you for replying. > {quote:title=kenwong wrote:}{quote} > Although it is possible to model an open end connector using 3-D E&M simulators, its usefulness is limited because of many ill defined physical structures. For the male connector for example, the male pin acts like an antenna. I was thinking of shielding the male pin, by screwing a female socket on, after removing the female pin and any PTFE insulation from the female socket. That will stop most if not all of the radiation, but does not get around the fact the pin shape is not well very defined by the MIL standard for an N connector. > The raidation characteristics is highly sensitive to the coupling nut's position and length. As I say, one can eliminate that by screwing a female socket on, with all the inner parts removed. That provides an inexpensive open which should not radiate. > The shape of the male pin tip is not well define and yet it has a first order impact on the radiation characteritics. Resonances within operating frequencies were also observed. For Type-N, the male pin is partially shielded but sets behind the outer conductor's mating plane. This set back creates any set of variables such as step impedance change. If the connector's dimensions are well control, it can be modeled and used below the resonance region. I've noticed the effect of the nut on an open male SMA far more than open male N, since the SMA male pin protudes into a region of space close to the nut, whereas even a totally unterminated N does provide a degree of shielding. But for my purposes, I am able to at least remove the effects of the nut, by screwing in a female N with all the inner parts removed. > An easier way to obtain the electrical characteristics is to do an accurate 1-port calibration, using the connector of interest as the test port connector. With error correction ON, measured the response of the open ended connector. That was how the FieldFox connector model generated. I tried that, but for some reason I got what I think were totally unrealistic results. Do you see anything wrong with my logic? This is what I did. 1) Assumed the thin part of the male pin which inserts into the female is a contant diameter. I know it tapers at the end, but that was ignored. Of course, this introduces some error, which you did not have since your standards were well defined. 2) Looked at MIL-C-39012C standard which shows the thin part of the male pin extends to a distance of between 0.208" to 0.211" behind the reference plane. Of course, this variability gives a problem, but I assume a mean value of 0.2095" behind the reference plane. 3) Assumed that the offset delay would be -17.775 ps, which is the case for a length of 0.2095" It would be negative, as the pin is behind the reference plane. 4) Did a one-port cal on the VNA, then set a port extension of -17.775 ps. 5) Measured the phase shift as a function of frequency from 50 MHz to 6 GHz. 6) Calculated the capacitance from the phase shift, assuming a resistance of 50 Ohms. Anyway, after doing that, I calculated a fringing capacitance varying from 211 fF at 50 MHz rising to 240 fF at 6 GHz, which seems a bit unrealistic to me. Perhaps I should have assumed a resistance greater than 50 Ohms, since the thin part of the pin would produce an offset Zo of > 50 Ohms. That would result in a reduced value for the capacitance, but the change with frequency would still be about 20%, which does not seem to be the case with any cal kit. > My paper deal with modeling of calibration standards that are well defined physically. The open standards are shielded opens with a supported center conductor and with a defined offset length. The fringing capacitance can be modeled nicely using today's 3-D E&M simulators. Back then, I had to use a comination of simulation tools including proprietary ones. OK, so you did not need to determine the offset delay, as you got this precisely from your measurements - something impossible with any standard connector. > Many papers had been publushed on the open capacitance topic, specifically on open ended coaxial line dielectric probes. The Waveguide Handbook by Marcuvitz, section 4.16 deals with coaxial line radiating into semi-infinite space. These models are more applicable for open ended female connectors. I found a lot of the papers, and found the maths too heavy! But they all seem to assume a groundplane infinite in extent, which is easy to make on a dielectric probe, but is not the case on an RF connector. Again, I thought an EM simulator might give me more insight into what is going on. I think the basic problem is I'm trying to do something more complex and less well defined than you. For your paper, you knew precisely the offset Zo and offset delay from purely physical measurements, so you only used the EM simulator to find capacitance. I'm trying to model a connector when neither the offset Zo or offset delay are precisely known. At the moment my two VNAs are on the dining table, much to the annoyance of my wife. I'm in the middle of decorating the house, so don't have easy access to my equipment. I will have to look at this again some time. Thank you for your help Ken. If you have any comments, feel free to add them. Dave |
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根据我在N-male连接器上的一些测量数据,开放式连接器型号需要86.6欧姆的偏移Zo和-7.7 pS延迟,以获得低于6 GHz的合理电容值。相位响应首先是电感性的,
然后电容。 我确实看到了6 GHz附近的一些共振行为。 并且在16.4 GHz附近更清晰。 盾牌肯定会消除这些共鸣。 以上来自于谷歌翻译 以下为原文 Based on some measurement data I had on the N-male connector, the open end connector model require a offset Zo of 86.6 ohms and a -7.7 pS delay to get a reasonable capacitance value below 6 GHz.. The phase response goes inductive first and then capacitive. I did see some resonant behavior near 6 GHz. and a sharper one at around 16.4 GHz. A shield will definitely remove those resonances. |
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60user22 发表于 2019-1-7 09:41 > {quote:title = kenwong写道:} {quote}>根据我在N-male连接器上的一些测量数据,开放式连接器型号需要86.6欧姆的偏移Zo和-7.7 pS延迟以获得合理的 电容值低于6 GHz ..相位响应首先是电感,然后是电容。 我确实看到了6 GHz附近的一些共振行为。 并且在16.4 GHz附近更清晰。 盾牌肯定会消除这些共鸣。 谢谢肯,这是最有用的。 如何测量偏移延迟和偏移Zo的这两个值? 如果我用校准套件校准VNA,那么让男性N打开,我将如何重现类似于你得到的结果? 我很欣赏我不会得到相同的,因为雄性针的形状没有明确定义,但我不知道你将如何衡量这些。 基于物理测量,我希望如此。 *针脚直径范围根据MIL规格= 0.0644“至0.0658” - 因此平均值为0.0651“(忽略其末端逐渐变细的事实)*根据MIL规格,外导体的内径为0.2753”至0.2759“ - 均值 这种传输线的0.2756“Zo = 60 * log_base_e(0.2756 / 0.0651)= 86.5816欧姆。 因此,您测量86.6欧姆的事实与我根据引脚的物理尺寸计算的非常相似。 但问题在于抵消延迟。 看看N连接器的MIL规格,我可以看到引脚的衰退应该在0.208“到0.211”的范围内,所以平均值为0.219“。将其转换为mm,得到25.4 * .219 = 5.5626 mm。 光速为3x10 ^ 8 m / s,因此偏移为-5.5626 mm,时间为-5.5626 x 10 ^ -3 / 3 x 10 ^ 8 = -1.8542 x 10 ^ -11 = -18.542 ps, 这与你的测量值-7.7 ps *非常不同。也许这个销的一端用PTFE埋入的事实意味着传播速度不高达3x10 ^ 8 m / s,尽管传输线是这样的 是空气,因为有些领域是PTFE。但即便如此,差异似乎有点难以解释。我很感兴趣如何测量VNA上的偏移Zo和偏移延迟。我知道有一个部分在 Joel的书中使用TDR函数测量自己的标准,但我的计算似乎表明,20 GHz VNA的时间分辨率不足以以任何精度测量这么小的距离。 使用更高频率的VNA可能会做得更好,N插头的额定值不高于18 GHz,所以如果将测量频率提高得更高以便获得更好的空间分辨率,我会期望得到各种各样的问题。 PS - 你做过博士学位吗? 在一个相关的主题? 你似乎对cal标准非常了解。 我自己的博士学位 是医学物理学,所以与此无关。 戴夫 以上来自于谷歌翻译 以下为原文 > {quote:title=kenwong wrote:}{quote} > Based on some measurement data I had on the N-male connector, the open end connector model require a offset Zo of 86.6 ohms and a -7.7 pS delay to get a reasonable capacitance value below 6 GHz.. The phase response goes inductive first and then capacitive. I did see some resonant behavior near 6 GHz. and a sharper one at around 16.4 GHz. A shield will definitely remove those resonances. Thank you Ken, that is most useful. How do you measure those two values for offset delay and offset Zo? If I were to calibrate the VNA with a cal kit, then leave the male N open, how would I reproduce results similar to what you get? I appreciate I would not get the same, for the reasons the shape of the male pin is not well defined, but I don't have a clue how you would measure those. Based on the physical measurements, I would expect. * Pin diameter range according to MIL spec = 0.0644" to 0.0658" - so a mean of 0.0651" (ignoring the fact it tapers at the end) * Inner diameter of outer conductor according to MIL spec is 0.2753" to 0.2759" - mean of 0.2756" Zo of such a transmission line = 60*log_base_e(0.2756/0.0651) = 86.5816 Ohms. So the fact you measured 86.6 Ohms is very similar to what I calculate from the physical dimensions of the pin. But the problem arrises on the offset delay. Looking at the MIL spec for the N connector, I can see the recession of the pin should be in the range 0.208" to 0.211", so a mean of 0.219". Converting that to mm, gives 25.4*.219= 5.5626 mm. The speed of light is 3x10^8 m/s, so an offset of -5.5626 mm, is a time of -5.5626 x 10^-3 / 3 x 10^8 = -1.8542 x 10^-11 = -18.542 ps, which is *very different* from your measured value of -7.7 ps. Perhaps the fact one end of the pin is burried in PTFE means the velocity of propogation is not as high as 3x10^8 m/s, despite the fact the transmission line is air, since some of the fields will be in PTFE. But even so, the difference seems a bit hard to explain. I'm interested how one could measure offset Zo and offset delay on a VNA. I know there is a section in Joel's book about measuring ones own standards using the TDR function, but my calculations seem to suggest the temporal resolution for a 20 GHz VNA is just not good enough to measure such small distances with any sort of accuracy. Whilst one might be able to do better with a higher frequency VNA, the N plug is not rated above 18 GHz, so I would expect one to get all sorts of problems if one pushed up the measurement frequency much higher in order to get better spacial resolution. PS - did you do a Ph.D. on a related subject? You seem very knowledgable on cal standards. My own Ph.D. is in medical physics, so quite unrelated to this. Dave |
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谢谢你的补充。
多年来,我在校准标准设备建模方面做了大量研究。 您无法使用网络分析仪测量偏移量Zo。 您可以根据dimentsions估算其值和延迟值,然后根据测量的S11数据拟合,以获得最佳拟合。 虽然你提到的物理效果较差,但是边缘场导致电长度变长。 您仍然可以使用物理延迟值来拟合一些电容值,但拟合将不是最佳的。 希望这可以帮助。 肯 以上来自于谷歌翻译 以下为原文 Thank you for your complement. I did quite a bit of research in calibrfation standard device modeling at work for many years. You can't measure offset Zo using a network analyzer. You can estimate its value and the delay value from dimentsions and then fit a funtion to the measured S11 data to get the best possible fit. Although the physical dealy is less as you mentioned, the fringing field caused the electrical lenght to be longer. You still can fit some capacitance value using the physical delay value but the fit will not be as optimum. Hope this helps. Ken |
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> {quote:title = kenwong写道:} {quote}>谢谢你的补充。 多年来,我在校准标准设备建模方面做了大量研究。 我以为你已经研究过这个了。 我知道你已经写了一些论文。 >您无法使用网络分析仪测量偏移量Zo。 您可以根据dimentsions估算其值和延迟值,然后根据测量的S11数据拟合,以获得最佳拟合。 所以我确定你给出的86.6欧姆的偏移量计算得出,这就解释了为什么我的86.5816欧姆的计算值非常接近。 >您仍然可以使用物理延迟值来拟合一些电容值,但拟合将不是最佳。 是的,我曾尝试将偏移长度设置为物理值,但效果不佳。 但我使用了50欧姆的偏移Zo,我可以看到它不是最佳的。 我将使用修正后的偏移量Zo再次尝试,但我明白为什么边缘场意味着最佳偏移长度与物理偏移长度不同。 >希望这会有所帮助。 是的,它确实。 它给了我几个关于如何改进我以前做过的事情的想法。 我将进行更多测量,并且我还将重新考虑模拟思路,因为HFSS将允许人们看到S11的值范围与不同形状的引脚一起获得,这对于测量来说不是那么容易 尝试有限数量的N连接器。 >肯非常感谢Ken。 你是一个丰富的信息! 戴夫 以上来自于谷歌翻译 以下为原文 > {quote:title=kenwong wrote:}{quote} > Thank you for your complement. I did quite a bit of research in calibrfation standard device modeling at work for many years. I thought you had reseached this quite a bit. I know you have written some papers on it. > You can't measure offset Zo using a network analyzer. You can estimate its value and the delay value from dimentsions and then fit a funtion to the measured S11 data to get the best possible fit. So I assue the offset Zo you gave of 86.6 Ohms was calculated, which explains why my calculated value of 86.5816 Ohms was very close. > You still can fit some capacitance value using the physical delay value but the fit will not be as optimum. Yes, I had tried the setting the offset length to the physical value, but it worked poorly. But I had used an offset Zo of 50 Ohms, which I can see is not optimal. I will try it again with a revised value of offset Zo, but I take your point about why the fringing fields will mean the optimal offset length is not the same as the physical one. > Hope this helps. Yes it does. It gives me several ideas on how to improve on what I had done before. I'll make some more measurements, and I will also revisit the simulation idea, as HFSS would allow one to see the range of values for S11 one gets with different shaped pins, which is not so easy to do with measurements as one can only try a limited number of N connectors. > Ken Thank you very much Ken. You are a wealth of information! Dave |
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N5230C用“CALC:MARK:BWID?”获取Bwid,Cent,Q,Loss失败,请问大佬们怎么解决呀
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