Your browser is out of date.

You are currently using Internet Explorer 7/8/9, which is not supported by our site. For the best experience, please use one of the latest browsers.

• Chrome
• Firefox
• Internet Explorer Edge
• Safari Phase Stability over Temperature for Low Loss Coaxial Cable

# Phase Stability over Temperature for Low Loss Coaxial Cable

## Phase Stability over Temperature Harbour created the above graph by measuring the time delay change of a 10ft length of LL Low Loss coax when subjected to the following conditions:

• Place the assembly in a cold box and oven chamber and connect to a Network Analyzer
• Soak the assembly for 2hrs at 20°C and record the initial measurement. This is the reference value Td (ref)
• Decrease the temperature to -55°C and soak for 1 hour before recording measurement. Td (@ temp)
• Raise the temperature at 20°C intervals; soak the assembly for 1 hour before recording data. Td (@ temp)
• Calculate ppm with 2 equations:
• 1st calculate the difference from the reference: ∆Td = Td(ref)-Td (at temp)
• 2nd calculate ppm using the formula: ppm = ∆Td(ref) x 106  / Td (ref)

Phase change occurs as a result of environmental changes: mechanical stresses, connector torque, and thermal conditions. Phase change is expressed in change of the electrical length (EL). Using the above information, phase change can be predicted by using the formula:

∆ EL = EL x (ppm/106)

Before calculating the excepted phase shift, a few additional questions need to be answered:

• What is the mechanical length of the assembly (ft.)?
• What is the frequency of interest (GHz)?
• What is the dielectric constant of the insulation (E)?
• What is the temperature of interest (°C)?
• What is the electrical length at the frequency of interest (EL)?

EL = 365.7 x √E x (ft) x (GHz)

For example, the phase change of a 10 ft. LL142 assembly at -35°C and at 18GHz is 15.32°

Step 1. Electrical length (EL)

EL = 365.7 x √1.5 x 10 x 18 = 80,620°

Step 2. Using the chart above identify the ppm at -35°C

ppm = 190

Step 3. Solve for the change in Phase (∆ EL)

∆ EL = 80,620° x (190/106) = 15.32°

## Interested in Learning More About Us?

Harbour Industries is the global leader in product engineering and manufacturing of high temperature and high-performance cable. Our product and process engineering expertise ensures the highest quality products manufactured to precise customer specifications.