进行校准与高值衰减器连接的PNA时需要特殊设置吗？

这里有几个问题。
首先，Cal All对校准中选择的所有端口执行源功率校准，默认情况下，您将获得2端口校准。
我将在这里继续讨论并假设您没有将通道中的端口功率分离，并将端口2功率设置得足够低以容纳40 dB衰减器。
换句话说，你试图在端口2上实现-30到0 dBm，损耗为40 dB，这意味着端口2上的源（在Cal All执行源功率校准后）必须输出+10到+40
在校准参考平面上获得-30到0 dBm的功率dBm，这就是为什么在衰减器就位的情况下光源不平整，并且在没有它或使用较小的衰减器进行校准时工作正常。
第二个问题是通过40 dB焊盘进行2端口s参数校正。
即使光源可以输出+ 40 dB，完全开路或短路的反射信号在到达端口2反射计时也会小于-80 dBm。
所以即使在最好的情况下你也会有一个非常嘈杂的S22，并且取决于你的DUT的反向隔离，也是一个非常嘈杂的S12。
通过完整的12项2端口纠错，这些噪声S22和S12参数会对您尝试进行的S21测量产生重大影响。
在这样的设置中，你最终测量的是40 dB衰减器的S22而不是DUT的S22。
解决方案是执行仅前向传输校准或我们称之为“增强响应”校准。
该方法校正输入匹配（S11）并用响应校正校正传输（S21）。
下图显示了在Cal All向导中必须遵循的过程，以便选择EnhResp方法。
请注意，此校准需要定义的Thru标准，如果您使用的是ECal，则ECal thru按定义使用。
如果您不使用ECal，则需要零或冲洗校准设置。
！HTTPS：//dl.dropbox.com/u/87949221/CalAll_EnhancedResp.jpg！



     以下为原文

  there are a couple of issues here. first, Cal All performs a source power calibration for all the ports selected in the calibration and by default you are getting a 2-port cal.  I am going to go on limb here and assume you did not uncouple the port powers in your channels and set the port 2 power to be low enough to accommodate the 40 dB attenuator.  In other words you are trying to achieve -30 to 0 dBm on port 2 with 40 dB of loss which means that the source on port 2 (after the source power calibration performed in Cal All) will have to put out +10 to +40 dBm of power to get -30 to 0 dBm at the calibration reference plane and that is why the source is going unleveled with the attenuator in place and works fine when you calibrate without it or with a smaller attenuator.

the 2nd problem is with the 2-port s-parameter correction through a 40 dB pad.  even if the source could put out +40 dB, the reflected signal of a perfect open or a short would be less than -80 dBm by the time it reached the port 2 reflectometer.  So even in the best case scenario you would have a very noisy S22 and depending on the reverse isolation of your DUT, also a very noisy S12.  with a full 12 term 2-port error correction, these noisy S22 and S12 parameters would have a significant impact on the S21 measurement you are trying to make.  In a setup like this what you end up measuring in essence is the S22 of the 40 dB pad and not the S22 of the DUT.  The solution is to perform a forward transmission only calibration or what we call the "Enhanced Response" calibration.  this method corrects the input match (S11) and the corrects the transmission (S21) with a response correction.  the following diagram shows the process you have to follow in the Cal All wizard in order to select the EnhResp method.  Note that this calibration requires a defined Thru standard and if you are using an ECal, then the ECal thru is used as defined thru.  if you are not using an ECal, then you need a zero or flush-thru calibration setup.

!https://dl.dropbox.com/u/87949221/CalAll_EnhancedResp.jpg!

Dara解决了这个问题，但要简洁：1）如果你将衰减（或增益）加到超过10 dB的端口，你应该使用功率/衰减器下的“功率偏移”：偏移和限制选择。
对于你的情况，使端口2的偏移= -40 dB。
2）你必须解开港口的权力。
使端口2功率=（端口1功率+近似增益 - 10 dB）并且，您无法真正通过40 dB衰减器进行测试，因此您不应使用完整的2端口校准。
如果要测量所有4个s参数，则必须使用前面提到的“微波元件测量手册”第6章中所述的高功率设置。
但是：如果您的DUT是高增益而非高功率，则无需使用40 dB衰减器。
增益有多高，输出功率有多高？



     以下为原文

  Dara covered the issue, but to be succinct:
1) if you add attenuation (or gain) to a port in excess of 10 dB, you should use the "power offsets" in under the power/attenuators:offsets and limits selection.  for you case, make the offset for port 2=-40 dB.

2) You must uncouple the port powers.  Make port 2 power = (port 1 power + approximate gain - 10 dB)

And, you cannot really cailbrate through a 40 dB attenuator, so you should not use a full 2 port cal.  If you want to measure all 4 s-parameters, you must use a high power setup as described in chapter 6 of the previously referred book, Handbook of Microwave Component Measurements.

BUT: if you DUT is high gain and NOT high power, no need to use the 40 dB attenuator.  How high is the gain, how high is the output power?

感谢Daras，drkirkby，bhokkan和Joel博士的回复;
对此，我真的非常感激。
回复drkirkby：我只有一个基本的2端口PNA N5222A（没有暴露的其他端口，如R，B等），并且拥有最新的PNA固件A.09.85。
我已经阅读了应用笔记“Agilent AN 1287-6使用网络分析仪来表征高功率组件”，我正在按照应用笔记使用配置1。
！HTTPS：//lh6.googleusercontent.com/-1hpQaU8U6zQ/UU6HKaAi3-I/AAAAAAAAAAk/xcIYRFPSyO0/s412/Config01.png！
回答Daras和bhokkan：是的，我没有解开港口。
我需要测量的只是输入VSWR（S11），增益平坦度（S21），增益线性度（不同频率下的功率扫描以找到压缩点）和一些脉冲测量（相位误差测量）。
由于我没有测量S22或S12，这是否意味着前向传输校准（增强响应校准）就足够了？
顺便说一下，我还在使用机械校准套件（虽然我之前已经购买了ECal）。
我将尝试增强响应校准。
回答Joel博士：如果我只需要测量输入VSWR，增益平坦度，增益线性度和一些脉冲测量值，那么前向传输是否足够？
我的放大器DUT是一个50 dB增益放大器，我希望它能从-30 dBm驱动到最大0 dBm。
这意味着我的最大输出功率约为50 dBm（60 W）。
再次提前感谢。
编辑：Engineer007于2013年3月23日11:20 PM编辑：Engineer007于2013年3月23日下午11:45



     以下为原文

  Thanks Daras, drkirkby, bhokkan and Dr Joel for the replies; I really appreciate it.

In reply to drkirkby:
I only have a basic 2-ports PNA N5222A (without other ports like R, B, etc exposed) and am having the latest PNA firmware A.09.85. I've read the app note "Agilent AN 1287-6 Using a Network Analyzer to Characterize High-Power Components" and I'm using Configuration 1 as per the app note.

!https://lh6.googleusercontent.com/-1hpQaU8U6zQ/UU6HKaAi3-I/AAAAAAAAAAk/xcIYRFPSyO0/s412/Config01.png!

In reply to Daras and bhokkan:
Yes, I did not uncouple the ports. What I need to measure is just the input VSWR (S11), gain flatness (S21) , gain linearity (Power sweep at different frequencies to find the compression point) and some pulse measurements (phase error measurements). Since I did not have to measure S22 or S12, does it mean that forward transmission cal (Enhanced Response cal) is sufficient here? By the way, I'm still using a mechanical cal kit (although I have put a purchase for an ECal sometime ago). I will try out the Enhanced Response cal.

In reply to Dr Joel:
If I only need to measure input VSWR, gain flatness, gain linearity and some pulse measurements, would forward transmission cal be sufficed here? My amplifier DUT here is a 50 dB gain amplifier and I expect to drive it from -30 dBm to 0 dBm max. This means I would have a max output power of about 50 dBm (60 W).

Thanks again in advance.

Edited by: Engineer007 on Mar 23, 2013 11:20 PM

Edited by: Engineer007 on Mar 23, 2013 11:45 PM

> {quote：title = Engineer007写道：} {quote}>回复Joel博士：>如果我只需要测量输入VSWR，增益平坦度，增益线性度和一些脉冲测量值，那么前向传输速率是否足够？
我的放大器DUT是一个50 dB增益放大器，我希望它能从-30 dBm驱动到最大0 dBm。
这意味着我的最大输出功率约为50 dBm（60 W）。
你的计算有问题，因为50 dB增益放大器的0 dBm会给你50 dBm，即100 W，而不是60 W.我想到的是衰减器特性随温度变化的可能性。
如果您在室温下测量其注意力，然后根据该值进行计算，如果高功率水平下的耗散会显着改变温度，则可能会引入误差。
几年前，当我大约15或16岁时，我建造了一个1千瓦的放大器，用于144 MHz的业余无线电使用。
这是基于一对Eimac 4CX250B阀门。
我从来没有一个额定功率为1 kW的推进器假负载，所以对于测试我有一个RG58同轴电缆的卷轴，这是足够的损耗，反射功率是微不足道的。
这是因为我施加的电源时间太长，在这种情况下，同轴电缆会熔化。
这种情况发生了很多次，但我只是习惯于寻找熔化的地方，切断坏的位置，并在同轴电缆上贴上新的N插头！
那些日子很有趣！
戴夫。



     以下为原文

  > {quote:title=Engineer007 wrote:}{quote}
> In reply to Dr Joel:
> If I only need to measure input VSWR, gain flatness, gain linearity and some pulse measurements, would forward transmission cal be sufficed here? My amplifier DUT here is a 50 dB gain amplifier and I expect to drive it from -30 dBm to 0 dBm max. This means I would have a max output power of about 50 dBm (60 W).

There's something wrong with your calculations, as  0 dBm into a 50 dB gain amplifier would give you 50 dBm, which is 100 W, not 60 W. 

Something that crossed my mind is the possibility of the characteristics of the attenuator changing with temperature. If you measure its attenation at room temperature, then make calculations based on that value, you could introduce an error if dissipation at high power levels changes the temperature significantly. 

Years ago, when I was about 15 or 16, I built a 1 kW amplifier for amateur radio use at 144 MHz. That was based on a pair of Eimac 4CX250B valves. I never had a propor dummy load rated at 1 kW, so for testing I had a reel of RG58 coax, which was sufficiently lossy that the reflected power was insignificant. That was unless I kept the power applied for too long, in which case the coax would melt. That happened many times, but I just used to look for where it had melted, cut the bad bit off, and stick a new N plug on the coax! Those days were fun!

Dave.