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我在简单测量天线传输测量时遇到了问题。
我有2个相距2米的对数周期天线。 天线的增益分别为6dBi。 根据理论计算，系统的损耗应约为27.7 dB。 这基于自由空间空气中的39.7 dB损耗+ 12 dB增益。 我有三台分析仪测量这个设置。 8720B / 001 / 010,8720ES / 010/012/089和E8364B / 010/014/016/080/081/083 / UNL。 我正在使用2米低损耗的戈尔网络分析仪电缆。 所有三个单元都按照MFR规范进行了完全校准。 该天线的VSWR为1.5 @ 1 GHz。 8720B测量天线系统的校正损耗@ 29.7 dB。 PNA测量校正损耗@ 27.6 dB。 8720ES测量损失@ 49.3 dB。 所有单位都设置为默认功率，8720B为-10 dBm，8720ES为+5 dBm，PNA为+10 dBm。 所有单位都设置为相同的IF BW，数据点和任何其他相关参数进行比较。 我检查了8720ES的原始耦合器回波损耗和源匹配，看看这是否是一个问题，因为这个单元在两个端口（S12，S21）和彼此的0.3 dB之间测量低。 所有装置也都进行了本底噪声测试，并且在预期参数范围内。 ES模型中是否存在可能导致此问题的硬件差异？ 我错过了ES中的设置吗？ 在传输校正中，我只是在天线之前在电缆系统的末端进行了简单的直通校准。 除了仅连接到测试端口的电缆外，没有放大器或其他设备在线。 乔尔博士，我希望你能解释一下这个问题。 谢谢，戴夫 以上来自于谷歌翻译 以下为原文 I am having an issue in the simple measurement of an antenna transmission measurement. I have two log periodic antennas 2 meters apart. The antenna's have a gain of 6dBi each. Based on theoretical calculations the loss of the system should be approximately 27.7 dB. This based on 39.7 dB loss in free space air + 12 dB gain. I have three analyzers measuring this set up. 8720B/001/010, 8720ES/010/012/089, and an E8364B/010/014/016/080/081/083/UNL. I am using 2 meter low loss Gore network analyzer cables. All three units have been fully calibrated per MFR specifications. The antenna has a VSWR of 1.5 @ 1 GHz. The 8720B measures the corrected loss of the antenna system @ 29.7 dB. The PNA measures the corrected loss @ 27.6 dB. The 8720ES measures the loss @ 49.3 dB. All units are set to default power, -10 dBm for the 8720B, +5 dBm for the 8720ES, +10 dBm for the PNA. All units are set to the same IF BW, data points and any other relevant parameter for comparison. I checked the 8720ES for raw coupler return loss and source match to see if this is could be a problem as this unit measures low on both ports (S12,S21)and within .3 dB of each other. All units were also tested for noise floor and were well within expected parameters. Is there a hardware difference in the ES model that would cause this problem? Is there a setting in the ES that I missed? In the transmission correction, I just did a simple thru calibration at the ends of the cable system before the antennas. There are no amplifiers or other devices in line except the cables to the test ports only. Dr. Joel, I hope you can help explain this one. Thanks, Dave 
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14个回答
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你试过减慢8720ES的扫描速度吗？
您可能需要使用此长度的电缆将其减速至低于默认速度。 随着频率被扫描，信号源被扫描并且接收器被扫描。 但是对于长电缆，延迟可能很大，因此源和接收器的频率不同，因此检测到的信号落在检测器的IF带宽之外。 顺便说一句，并不是说它应该在不同的VNA上产生不同的结果，但你可能太接近于假设自由空间条件，所以我不相信简单的自由空间路径损耗计算。 通常，如果天线的最大尺寸是D，以及天线L之间的间距，则您希望所有这三个条件都成立。 1）L >> D（比如10x）2）L >>λ（比如10x）2）L> 2D * D /λ。 2 m不是10 GHz波长，1 GHz。 戴夫 以上来自于谷歌翻译 以下为原文 Have you tried slowing down the sweep speed of the 8720ES? You may well need to slow it below the default speed with this length of cables. As the frequency is swept, the source is swept and the receiver is swept. But with long cables the delay can be significant, so the source and receiver are then not at the same frequency, so the detected signal falls outside the IF bandwidth of the detector. BTW, Not that it should result in different results on different VNA, but you are probably too close to assume free space conditions, and so I would not trust a simple free space path loss calculation. Generally, if the largest dimension of an antenna is D, and the spacing between the antennas L, you want all 3 of these conditions to be true. 1) L >> D (say 10x) 2) L >> lambda (say 10x) 2) L > 2 D*D/lambda. 2 m is not 10 x the wavelength at 1 GHz. Dave |
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> {quote：title = drkirkby写道：} {quote}>你试过减慢8720ES的扫描速度吗？ 很好的猜测，我会说。 较早的8720（我不认为有一个8720B，只有一个A和一个C）的预设是踩扫。 8720es的预设被扫除，这意味着IF延迟问题会更加普遍。 以上来自于谷歌翻译 以下为原文 > {quote:title=drkirkby wrote:}{quote} > Have you tried slowing down the sweep speed of the 8720ES? Pretty good guess, I'd say. Preset on the older 8720's (I don't think there was an 8720B, just an A and a C) was stepped sweep. Preset on the 8720es was swept, meaning IF delay issues would be more prevalent. |
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脑洞大赛9 发表于 2018-11-20 21:11 Joel，我将尝试步进扫描功能并使用驻留和数据点。 此外，PNA是否已默认步进或扫描。 如果横扫，为什么不是同样的问题。 8720B于1990年3月推出，于1991年9月停产。戴夫 以上来自于谷歌翻译 以下为原文 Joel, I will try the step sweep function and play with the dwell and data points. Also, does the PNA have stepped or swept as default. If swept, why not the same problem. The 8720B was introduced in Mar 1990 and discontinued Sept 1991. Dave |
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脑洞大赛9 发表于 2018-11-20 21:11 Joel，我将尝试步进扫描功能并使用驻留和数据点。 此外，PNA是否已默认步进或扫描。 如果横扫，为什么不是同样的问题。 8720B于1990年3月推出，于1991年9月停产。戴夫 以上来自于谷歌翻译 以下为原文 Joel, I will try the step sweep function and play with the dwell and data points. Also, does the PNA have stepped or swept as default. If swept, why not the same problem. The 8720B was introduced in Mar 1990 and discontinued Sept 1991. Dave |
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PNA具有更宽的默认带宽，因此延迟效果更小。 您使用的是什么IF BW？ PNA以1kHz以下的速度进入步进模式，在30Hz及以下时为8720ES，我认为这是默认步骤。 以上来自于谷歌翻译 以下为原文 PNA has wider default bandwidths so the delay effect is less. What IF BW are you using? PNA snaps to step mode at 1kHz an below, 8720ES at 30Hz and below, 8720B was default in step, I think. |
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脑洞大赛9 发表于 2018-11-20 21:36 测试带宽为100 Hz，所有三个分析仪均为401个数据点。 当分析仪再次可用时，我将能够在周一测试设置，并能够报告我的发现。 乔尔和戴夫，感谢您对此事的投入。 我会就我的发现提出建议。 此致，戴夫汉密尔顿 以上来自于谷歌翻译 以下为原文 The test bandwidth was 100 Hz, 401 data points for all three analyzers. I will be able to test the set up on Monday when the analyzer is available again and be able to report my findings. Joel and Dave, thanks for your input into this matter. I will advise as to my findings. Regards, Dave Hamilton |
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小佳99 发表于 2018-11-20 21:44 在100 Hz时，PNA始终处于步进扫描模式。 8720B可能处于步进模式，而8720ES可能不处于阶梯模式。 你在做什么校准？ 对于8720B而言，对于PNA，2 dB偏移量似乎很大，但如果您的设置发生变化则不会太不合理。 仅响应校准可能在分析仪和天线之间存在不匹配，如果天线不是特别匹配，则可能会导致差异超过dB。 以上来自于谷歌翻译 以下为原文 at 100 Hz the PNA is in stepped sweep mode always. THe 8720B is probably in stepped mode, and the 8720ES is probably NOT in stepped mode. What calibration are you doing? 2 dB offset seems big for 8720B vs PNA, but not so unreasonable if your setting changes. Response only calibrations can have mismatches between the analyzers and the antenna which can account for more than a dB of difference if the antenna's are not particularly well matched. |
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Joel博士和Kirby博士，阶梯式扫描功能确实纠正了这个问题。 一旦ES被改变，响应与其他两个相比就像预期的那样。 测量值在PNA的0.5 dB范围内。 我确实改变了扫描时间，它没有那么重要的变化和扫描类型。 奇怪的是，所有三种产品都有不同的默认扫描设置。 对于我正在执行此演示的一些技术人员和用户来说，这个问题是一个很好的例子，用于验证测试设置的性能。 通过检查与预期相比确保它正常工作，而不假设一切正常。 许多我知道只是开始测量，然后找出结果是无效的，没有线索为什么。 现在，当我有机会时，我会将他们带到认证范围并展示测量的微调，以获得有效的可量化结果。 Joel博士，是的，我同意你对模型之间差异的陈述。 我将审查所有三个性能设置差异，并尝试完成标准配置测量模板。 有了这个，我将对范围进行实际测量，并希望在测量不确定度内得到预期的结果。 以上来自于谷歌翻译 以下为原文 Dr. Joel and Dr. Kirby, The stepped sweep function did correct the problem. As soon as the ES was changed the response compared to the other two was as expected. The measurement was within .5 dB of the PNA. I did alter the sweep times and it did not have as significant of change and the sweep type. It is odd how all three products have different default sweep settings. This problem was a good example for some of the technicians and users I was performing this demo for, as to verify, the performance of the test set up. To ensure that it is working correctly by checking vs. expected, without assuming all is well. Many I have known just start measuring, then to find out the results are not valid and no clue as to why. Now, when I have an opportunity I will take them to a certified range and demonstrate the fine tuning of the measurement to get valid quantifiable results. Dr. Joel, Yes, I do agree with you statement of the differences between the models. I am going to review all threes performance setting differences and try to complete a standard configuration measurement template. With this I will then perform the actual measurements on range and hope to get the results expected within measurement uncertainty. |
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小佳99 发表于 2018-11-20 22:06 > {quote：title = dhamilton写道：} {quote}>这三种产品的默认扫描设置不同，这很奇怪。 唐，下次我们见面，你给我买了一个苦，我会告诉你整个细长的故事。 有时候我会占上风，有时我会胜利。 但是现在我有权威地说话，无论我在技术上是否正确。 以上来自于谷歌翻译 以下为原文 > {quote:title=dhamilton wrote:}{quote} > It is odd how all three products have different default sweep settings. And Don, next time we meet, and you buy me a bitter, I will tell you the whole elongated story. Sometimes I prevail, sometimes I am prevailed upon. But now I speak with authority, whether I'm technically correct or not. |
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> {quote：title = drkirkby写道：} {quote}>你试过减慢8720ES的扫描速度吗？ 很好的猜测，我会说。 较早的8720（我不认为有一个8720B，只有一个A和一个C）的预设是踩扫。 8720es的预设被扫除，这意味着IF延迟问题会更加普遍。 以上来自于谷歌翻译 以下为原文 > {quote:title=drkirkby wrote:}{quote} > Have you tried slowing down the sweep speed of the 8720ES? Pretty good guess, I'd say. Preset on the older 8720's (I don't think there was an 8720B, just an A and a C) was stepped sweep. Preset on the 8720es was swept, meaning IF delay issues would be more prevalent. |
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脑洞大赛9 发表于 2018-11-20 22:22 Joel，我将在ES上尝试逐步扫描功能。 PNA默认扫描还是踩扫？ 如果横扫，为什么它没有作为ES的延迟问题？ 谢谢，戴夫 以上来自于谷歌翻译 以下为原文 Joel, I will try the stepped sweep function on the ES. Does the PNA default to swept or stepped sweep? If swept, how come it doesn't have the delay issues as an ES? Thanks, Dave |
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戴夫，我会尝试慢速扫描。 然而，另外两个分析仪处于默认扫描状态，结果接近我的预期。 在距离上，如果我正在设置一个完整的测量范围，那么我将使天线至少保持10米。 这只是初步测试，看看系统是否会给出预期的结果，并在一个小环境（实验室）中展示配置对于没有看到天线如何在计量环境中使用的人的样子。 有两种工具，一种没有。 这是我的问题，为什么？ 戴夫 以上来自于谷歌翻译 以下为原文 Dave, I will try the slower sweep. However, the two other analyzers were at there default sweeps and the results were close to what I had expected. On the distance, if I were setting up a full measuring range then yes I would have the antennas at at least 10 meters. This was just preliminary testing to see if the system would give expected results and to demonstrate in a small environment (lab) what the configuration would look like to a person who had not seen how antennas are used in a metrology environment. Two instruments did, one did not. That was my question, why? Dave |
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戴夫，我会尝试慢速扫描。 然而，另外两个分析仪处于默认扫描状态，结果接近我的预期。 在距离上，如果我正在设置一个完整的测量范围，那么我将使天线至少保持10米。 这只是初步测试，看看系统是否会给出预期的结果，并在一个小环境（实验室）中展示配置对于没有看到天线如何在计量环境中使用的人的样子。 有两种工具，一种没有。 这是我的问题，为什么？ 戴夫 以上来自于谷歌翻译 以下为原文 Dave, I will try the slower sweep. However, the two other analyzers were at there default sweeps and the results were close to what I had expected. On the distance, if I were setting up a full measuring range then yes I would have the antennas at at least 10 meters. This was just preliminary testing to see if the system would give expected results and to demonstrate in a small environment (lab) what the configuration would look like to a person who had not seen how antennas are used in a metrology environment. Two instruments did, one did not. That was my question, why? Dave |
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尽管8720ES与其他两个VNA的差别很大，但它们都没有在可能被认为是合理的实验误差的范围内给出结果。
* 8720B表示29.7 dB。 * PNA表示27.6 dB这是2.1 dB的差异，因此在VNA测量的背景下是很大的。 尽管8720ES显示49.3 dB，这显然还有很长的路要走，但我认为您需要考虑3个VNA会产生3种截然不同的结果。 虽然您为所有三个VNA使用相同的IF带宽，但它们可能具有不同的扫描时间，不同的滤波器形状等，所有这些都可能导致问题。 祝你好运。 戴夫 以上来自于谷歌翻译 以下为原文 Although the 8720ES differs more than the other two VNAs, neither of them are giving results within what might be considered reasonable experimental errors. * The 8720B indicated 29.7 dB. * The PNA indicated 27.6 dB That's a difference of 2.1 dB, so is massive in the context of VNA measurements. Although the 8720ES indicates 49.3 dB, which is clearly a long way away, I think you need to consider that 3 VNAs are giving 3 very different results. Although you used the same IF bandwidth for all three VNAs, they might well have different sweep times, different filter shapes etc, all of which could contribute to problems. Good luck. Dave |
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