Phase stability vs. temperature is a measure of the signal speed variation when the cable is exposed to different temperatures. The temperature variation will induce the change of the dielectric constant εr, mechanical length, material character which will cause its phase variation. This variation can be unidirectional or multidirectional. The phase variation is characterized by the temperature coefficient of phase ηt, and the maximum variation of temperature coefficient of phase Δ|η|max
ηt = (φ25℃ - φt) / Φ25℃ Δ|η|max = |ηmax - ηmin|
where
φ25℃ is the phase at temperature 25℃, in (°)
φt is the phase at temperature t, in (°)
Φ25℃ is the total phase at 25℃, in (°)
Δ|η|max is the maximum phase variation coefficient, in ppm
Test Equipment
A vector network analyzer (VNA), a temperature chamber.
Test Sample
The test cable shall be 3 m long and terminated with suitable connectors at each end.
Test Procedure
1.Test sample shall be put into a temperature chamber in loose coils with the diameter not less than 10 times the cable’s minimum static bending radius. Adjust temperature of the chamber for 6 cycles and maintain at least 30 min at each limit temperature (85℃ and -55℃).
2.Set the temperature chamber to 85℃ and maintain 10 min at least when it reaches the temperature. Connect Test sample with the VNA, test Φ25℃ and φ25℃.
3.Adjust the tempe
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