Top test & measurement posts on EDAboard this week

Here are some of the most viewed posts on test and measurement topics from our EDAboard.com sister site this week:

Measuring capacitance: “I am going to make a circuit for measuring capacitance….I want to convert a differential capacitance to voltage. I have found many designs which use a timer. Is a timer mandatory? The circuit needs to be accurate for measuring capacitors in the picofarad range. The timer will measure the capacitance by altering frequency but I do not know what to do with the time output. I want to know whether there is another way to make this measurement without the timer.” Read more.

Open-source code for dielectric measurements: “There are a number of methods of measuring the dielectric properties (both permittivity and loss) of materials with a vector network analyzer…..Making up the hardware for any of these methods does not require a big effort, but converting VNA measurements to dielectric properties does…..The Keysight (formally Agilent) 85071E Materials Measurement Software does some/all of these methods, but starts at over $7,000…. So I am just wondering if anyone is aware of any software on these methods, or even a paper that does not require a degree in maths to understand so I can write the software myself.” Read more.

Dielectric strength: “I have a piece of equipment (with PCB) where the maximum voltage is 300 V between adjacent traces. What determines the dielectric strength test level for such a piece of equipment?” Read more.

Antenna measurements: “I know the definition of the axial ratio of an antenna. It is the ratio of the transverse components of the E-field of a particular antenna (a circularly polarized antenna). I also know how to get the axial ratio (dB vs frequency graph) from computer simulations. Now if I measure the far-field patterns of my fabricated antenna in an EMC chamber, how do I calculate the axial ratio from (dB vs scanning angle) data I get from measurements?” Read more.

De-embedding a test fixture: “De-embedding is the act of taking data that is measured in a test fixture and removing the effects of the fixture so the data is accurate to reference planes that are more useful, using vector measurements of known standards…. My question is what does the de-embedding process account for? Is it only the attenuation due to the test fixture involved? Or can we extract parameters such as the dielectric or conductivity of a DUT in a transmission line using this? … Can anyone tell me if de-embedding can be done using simulation software? Or can this process only be performed in practice (while measuring)?” Read more.