PCB Power Bus with Cable

power bus with cable over a ground plane

Modeling a printed circuit board alone in free space can be challenging, but printed circuit boards usually have cables attached to them and are nearly always tested above a conducting ground plane. Adding a cable and a ground plane to the geometry of the previous problem significantly complicates the modeling process. Several codes are not capable of modeling this geometry and nearly all of the codes have difficulty with it. This problem incorporates many basic features typically found in practical problems of interest to EMC engineers.

Modeling Notes:

  • The wire has a circular cross section with a 2-mm radius. However, equivalent results can be obtained by modeling the wire with a flat ribbon that has an 8-mm width.

  • The radiated field plots exhibit peaks corresponding to board cavity resonances (above 500 MHz) as well as lower-frequency peaks corresponding to resonances associated with the cable-board structure.

PCB & Cable Dimensions
PCB size125 mm × 100 mm × 1 mm
Cable length1 m
Cable radius2 mm

PCB & Cable
Materials

 All conductors (plates and cable) are perfectly conducting.
Board Dielectric: FR4, εr = 4.5, dielectric loss tangent = 0.015

Ground Plane

 Location: 1 m below the PCB board
Size: infinite
Material: PEC

Excitation

 Voltage Source (1 V, 50 ohms ) or Current Source (0.02 A, 50 ohms )
Location: middle of the short edge, between the PCB planes

Outputs
  1. Plot of electric field ( 5 MHz - 2 GHz, 10 m, θ=0°, φ=0° )
  2. Plot of electric field ( 5 MHz - 2 GHz, 10 m, θ=90°, φ=0° )
  3. Plot of electric field ( 5 MHz - 2 GHz, 10 m, θ=90°, φ=90° )
  4. Plot of electric field ( 5 MHz - 2 GHz, 10 m, θ=90°, φ=180° )