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All I can find on google is about what the dielectric loss angle is.
I imagine the bridge is something like a Whitstone bridge but for this...
Thanks
I imagine the bridge is something like a Whitstone bridge but for this...
Thanks
Oliver & Cage, AC Bridges (?).
Here's a thorough app note on the topic:
http://cp.literature.agilent.com/litweb/pdf/5989-2589EN.pdf [Broken]
Here are links to some of the equipment needed:
http://www.keysight.com/en/pd-1000000508:epsg:pro-pn-16453A/dielectric-material-test-fixture?cc=US&lc=eng
http://www.etesters.com/see/Dielectric_Constant/Fixtures
The simplistic answer is that nobody uses bridges anymore to measure dielectric properties of materials. Nowadays, an impedance analyzer takes the place of a bridge. The idea is to place a sample of the material in a suitable fixture which is usually a pair of metal plates with the dielectric material between them, making a capacitor. Then the real part of the impedance of the fixture gives a measure of the losses of the material being measured.
The dielectric loss of a capacitor is a resistive component that combines with the reactance of the capacitor to give a complex impedance. Now consider an AC bridge used to compare capacitor ratios.
With a simple amplitude detector the null will not be deep due to the fact that it is comparing a reactive C reference with a complex C lossy, that is with some resistive component. The single bridge balance adjustment will not give an accurate result. The detected signal can be minimised, but it will not be zero and the exact value of C will be indeterminate because of the wider null region.
With a synchronous detector the ratio of capacitance only will be accurately determined, there will be no influence from the resistive dielectric losses.
If an adjustable phase shift network is introduced before a simple differential amplitude detector then both the magnitude of the capacitance and the phase angle of the dielectric loss can be balanced accurately by searching for the deepest null. That is a “dielectric loss angle bridge”. Any failure to null at zero will be due to harmonic distortion of the AC test signal used.