Patent ID: 7535685

Claim:
A radio frequency (RF) signal coupler ( 120 ) comprising: a signal lead ( 123 ) for connecting to a low voltage terminal ( 114 ) of a shunt device ( 110 ), a ground lead ( 132 ) for connecting to earth ground, a coupling transformer ( 130 ), and an impedance matching and protection circuit ( 121 ), wherein the coupling transformer ( 130 ) comprises: a ferrite ring ( 124 ) having a central hole formed therein, a primary winding ( 126 ) 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 ( 119 ) and a second end ( 119 ′), the first end being connected to the signal lead ( 123 ) and the second end being connected to the ground lead ( 132 ), and a secondary winding ( 125 ) having multiple turns passing around a portion of the ferrite ring so as to pass through the hole of the ring, said secondary winding having two terminals ( 225 , 226 ), wherein the impedance matching and protection circuit ( 121 ) comprises: two input ends ( 401 , 402 ) and two output ends ( 403 , 404 ), the two input ends being connected to the two terminals of the secondary winding of the coupling transformer ( 225 , 226 ), respectively, the two output ends being connectable to an RF modem, a gas discharge tube ( 410 ) connected between the two input ends ( 401 , 402 ), an RF transformer ( 420 ) having a primary winding and a secondary winding, the primary winding being connected to the two input ends ( 401 , 402 ) and the secondary winding being connected to the two output ends ( 403 , 404 ), a transient voltage suppression (TVS) diode array ( 430 ), connected between the two output ends ( 403 , 404 ), and a resistor ( 440 ) being connected between the two output ends ( 403 , 404 ) for providing a dominating characteristic impedance, and wherein in the coupling transformer the ratio of turns of the secondary winding ( 125 ) to the turns of the primary winding ( 126 ) is at least two to one.