Radio frequency signal coupling system

A method for injecting or extracting an RF signal to or from an AC electrical power network via a shunt device having a high voltage terminal and a low voltage terminal and a coupler, the coupler comprising a signal lead for connecting to the low voltage terminal of the shunt device, a ground lead, and a coupling transformer, the coupling transformer comprising

• a ferrite ring having a central hole formed therein,
• a primary winding having multiple turns passing around a portion of the ferrite ring so as to pass through the hole of the ring, said primary winding having a first end and a second end, the first end being connected to the signal lead and the second end being connected to the ground lead, and
• a secondary winding having multiple turns passing around a portion of the ferrite ring so as to pass through the hole of the ring, wherein the ratio of turns of the secondary winding to the turns of the primary winding is at least two to one, and wherein said secondary winding has two ends for providing the RF signal to the RF modem,
• said method comprising the steps of:
• connecting the high voltage terminal of the shunt device to an electrical cable of the power network;
• connecting the low voltage terminal of the shunt device to the coupler;
• connecting the ground lead to earth ground;
• and
• injecting or extracting the RF signal to or from an RF modem connected to the coupling transformer.

A system for coupling a radio frequency (RF) signal to or from a medium voltage (MV) cable of a electrical power network, comprising

• a shunt device having a high voltage terminal connected to the MV cable and a low voltage terminal, and
• a coupler for cooperative engagement with the shunt device and for cooperative engagement with an RF modem so as to communicate an RF signal with the RF modem, comprising:
• a signal lead for connecting to the low voltage terminal of the shunt device,
• a ground lead for connecting to earth ground, and
• a coupling transformer, comprising:
• a ferrite ring having a central hole formed therein,
• a primary winding having multiple turns passing around a portion of the ferrite ring so as to pass through the hole of the ring, said primary winding having a first end and a second end, the first end being connected to the signal lead and the second end being connected to the ground lead, and
• a secondary winding having multiple turns passing around a portion of the ferrite ring so as to pass through the hole of the ring, wherein the ratio of turns of the secondary winding to the turns of the primary winding is at least two to one, and wherein said secondary winding has two ends for providing the RF signal to the RF modem.