| Engineering Notes |
| |
 Download PDF PPM Calculations
The electrical phase length of any coaxial cable will change over temperature. To calculate
the expected phase change of a Dynawave cable for any given temperature ranges use the
following method.
Example: Calculate the phase change of a 36 inch long DF118 assembly at -30oC at 12 GHz.
Determine the absolute phase (v) of the assembly at 25oC.
| δ = |
5.904 x Velocity of Propagation (VP) |
= |
5.904 x 0.78 |
= .002132 in/o |
| |
180 x freq (GHz) |
|
180 x 12 |
|
| ω = |
36 in |
= |
36 in |
= 16,885.55o |
|
δ |
|
002132 in / o |
|
• From the DF100 Series PPM Charts -30oC produces 1300 PPM of phase change
| φ = |
ω X (PPM) |
= |
16,886.55o X 1300 |
= 21.95o |
|
106 |
|
1,000,000 |
|
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| Useful Cable Assembly Formulas |
| |
| Attenuation: α = [K1 x √ | freq (GHz) | ] + [K2 x freq (GHz)] (dB/100 ft) |
| Wave length: λ = |
11.803 x Vp | (in) |
| |
freq (GHz) |
|
Characteristic Impedance: Zo = 60 x Vp x In (D/d) ohms
| Time Delay: T = |
1.016 | (nS/ft) |
| |
Vp |
|
| Cut Off Frequency: FC = |
7.5 x VP | (GHz) |
| |
D + d |
|
Length Given Delay: L = .9835 x T x Vp (ft)
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