Category Archives: dielectric constant

More dielectric constants

Since these are so hard to find, I’m going to record all findings. According to a 1961 document called Plastic-Film-Dielectric Capacitors by C. B. Charlton, high density polyethylene is 2.2, and low density polyethylene is 2.25. Polystyrene is 2.55. Polycarbonate … Continue reading

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More on transmission lines

PTFE has a more constant (!) dielectric constant over a reasonable frequency range (not that the 4 ohms delta of Kynar from 1MHz to 100MHz is a particularly significant amount), and apparently PTFE’s constant is about 2.1. Farnell sells wire … Continue reading

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Transmission line calculation tool

Since the steps were too much, this excel file was created. In the spreadsheet, the green values can be entered, and it will calculate the characteristic impedance, and the twists per inch for a given twist pitch angle. It will … Continue reading

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Twisted pair transmission line

For constructing transmission lines, coax is useful because it is available in 50 and 75 ohms. For transmission line transformers, the coax can be used, but it is quite thick. Twisted pair or parallel pair wires can be useful in … Continue reading

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