Calibration of HF Spectrum Analyzer

In summary, a network analyser can be used to calibrate a high-frequency spectrum analyzer for forward or reverse. There is no standard when it comes to which is considered forward. The orientation of connectors does not matter. The calibration is usually done with standard terminations, mis-matches and attenuators, but you can buy these.
  • #1
sandy.bridge
798
1
Hey guys,

Cannot seem to find the answer to my question within the Owners Manual for our high-frequency spectrum analyzer. When performing the 2-port calibration, it gives the option of testing in forward or reverse, which is a function of the test cable's orientation (male or female). Is it the male orientation that would be considered forward or reverse, and why exactly?
 
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  • #2
Are you talking about a network analyzer?

What is the make & model?
 
  • #3
Also, by "forward" and "reverse" I assume you mean S12 or S21.

Regardless, the orientation of the connectors does not matter; and there is no standard when it comes to which one is considered "forward".
 
  • #4
Calibration of this sort of thing is usually done with standard terminations, mis-matches and attenuators, afaik. You can buy these.
 
  • #5
It's been years since I used a network analyser but I remember that you perform the calibration on each cable that will connect to the device.

Let's say for example that you are going to test an amplifier. You'll have two coaxial cables from the analyser connecting to the input and output of the amplifier. For the calibration you simply loop the amp's input cable from the output of the analyser back to the input of the analyser (not the amp) then run forward calibration. Next you connect the cable that will be on the amp's output and run backward calibration.

This tells the analyser about the properties of the cables that will be connected to the amp. Specifically, it learns about the phase length and attenuation of the cables so that it can correct for this. Now when you run the test on the amp the analyser will eliminate the effects of the cables and only report the scattering parameters of the amplifier in question.

Some devices are single-ended. An antenna is a good example. In this case your analyser should have a different procedure where you connect standard loads to the end of your cable. It should be a short circuit, open circuit, and standard load. The standard load will be 50-Ohm for a 50-Ohm cable, 75-Ohm for a 75-Ohm cable, and so on. The calibration will again tell the device about the properties of the cable so that it can be eliminated from the results.

edit:

I think analysers use the standard load calibration on both cables used for 2-port devices. The forward calibration is for the cable that goes to the input of the device being tested and the back calibration should be for the output the device.
 
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  • #6
Another thing you need is an adjustable compensating length of cable in the reference path to take your reference plane to where you want the actual measurement to refer. (To 'unscrew' the phase rotation that unequal lengths will give you.) Without this, you will have no idea whether the mismatches are capacitative or inductive and any phase change may be swamped by cable delay.
 

What is calibration of a HF spectrum analyzer?

Calibration of a HF spectrum analyzer is the process of adjusting and verifying the accuracy of the instrument's frequency and amplitude measurements. This ensures that the readings are precise and reliable for accurate analysis of signals.

Why is calibration important for a HF spectrum analyzer?

Calibration is important for a HF spectrum analyzer because it ensures that the instrument is functioning correctly and providing accurate measurements. This is crucial for accurate analysis and troubleshooting of signals in various applications.

How often should a HF spectrum analyzer be calibrated?

The frequency of calibration depends on the specific instrument and its usage. Generally, it is recommended to calibrate a HF spectrum analyzer at least once a year or whenever there are significant changes in the instrument's environment or usage.

Can I calibrate my HF spectrum analyzer myself?

While it is possible to perform basic calibration procedures on a HF spectrum analyzer, it is recommended to have a professional calibration service or the manufacturer perform the calibration. This ensures that the instrument is calibrated correctly and to the necessary standards.

What are the consequences of not calibrating a HF spectrum analyzer?

Not calibrating a HF spectrum analyzer can result in inaccurate readings and measurements, leading to incorrect analysis and troubleshooting. This can have serious consequences in industries where precise measurements are crucial, such as telecommunications, aerospace, and defense.

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