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Title: Broad band directional signal generator
Claims: What is claimed is: 1. A broad band directional signal generator for generating signals on a transmission line or the like which, controllably, propagate in one direction on the line due to reinforcement of signals to the exclusion of the other direction due to cancellation of signals, or simultaneously, in opposite directions, comprising: a. an attenuator network employing linear, nonreactive impedance elements for insertion in said transmission line, said impedance elements forming at least first and second nodes; b. at least a first input terminal for receiving a first signal which is to propagate in said one direction on said transmission line; and c. first isolation means for coupling said first input terminal to said first node and for coupling said first input terminal to said second node, said first isolation means coupling said first signal at said first input terminal to said first and second nodes in a first predetermined ratio to cause a signal proportional to said first signal to propagate on said line in said one direction to the exclusion of said other direction. 2. A broad band directional coupling circuit as recited in claim 1 further comprising a second input terminal for receiving a second signal which is to propagate in said other direction in said transmission line, and second isolation means for coupling said second input terminal to said second node and for coupling said second input terminal to said first node, said second isolation means coupling said second signal at said second input terminal to said second and first nodes in a second predetermined ratio to cause said second signal to propagate on said line in said other direction to the exclusion of said one direction. 3. A broad band directional coupling circuit as recited in claim 2 wherein said first and second isolation means each comprise active devices. 4. A broad band directional coupling circuit as recited in claim 3 wherein said attenuator network is a .pi. attenuator network having a series impedance and first and second shunt impedances and the junction of said series impedance with said first shunt impedance defines said first node and the junction of said series impedance with said second shunt impedance defines said second node. 5. A broad band directional coupling circuit as recited in claim 4 wherein said first isolation means provides differential amplification with a ratio of amplification factors corresponding to said first predetermined ratio, and said second isolation means provides differential amplification with a ratio of amplification factors corresponding to said second predetermined ratio. 6. A broad band directional coupling circuit as recited in claim 5 wherein said first isolation means comprises a first voltage to current converting amplifier having a first transconductance and a second voltage to current converting amplifier having a second transconductance, said first amplifier having its output connected to said first node and said second amplifier having its output connected to said second node, the inputs of said first and second amplifiers being coupled to said first input terminal, and wherein said second isolation means comprises a third voltage to current converting amplifier having a third transconductance and a fourth voltage to current converting amplifier having a fourth transconductance, said third amplifier having its output connected to said second node and said fourth amplifier having its output connected to said first node, the inputs of said third and fourth amplifiers being coupled to said second input terminal. 7. A broad band directional coupling circuit as recited in claim 6 wherein said attenuator network is symmetrical, said first and third transconductances are equal to a transconductance, g.sub.1, and said second and fourth transconductances are equal to a transconductance, g.sub.2, said transconductances being defined by the following equations: ##EQU8## where Z.sub.0 is the characteristic impedance of the transmission line and K is the attenuation factor of the attenuator network. 8. A broad band directional coupling circuit as recited in claim 5 wherein said first and second shunt impedances are each comprised of two series impedances, the junctions of said two series impedances each defining third and fourth nodes, respectively, and wherein said first isolation means comprises a first push-pull amplifier having positive and negative outputs, the positive output of said first push-pull amplifier being connected to said first node and the negative output of said first push-pull amplifier being connected to said fourth node, and said second isolation means comprises a second push-pull amplifier having positive and negative outputs, the positive output of said second push-pull amplifier being connected to said second node and the negative output of said second differential amplifier being connected to said third node. 9. A broad band directional coupling circuit as recited in claim 8 wherein said attenuator network is symmetrical and said two series impedances have values, R.sub.1A and R.sub.1B, defined by the following equations: ##EQU9## where R.sub.1 is the value of each of said first and second shunt impedances and K is the attenuation factor of said attenuator network. 10. A broad band directional coupling circuit as recited in claim 3 wherein said attenuator network is a 0 attenuator network having first and second series impedances and first and second shunt impedances, and the junction of said first series impedance with said first shunt impedance defines said first node and the junction of said first series resistance with said second shunt impedance defines said second node. 11. A broad band directional coupling circuit as recited in claim 10 wherein said first isolation means provides differential amplification with a ratio of amplification factors corresponding to said first predetermined ratio, and said second isolation means provides differential amplification with a ratio of amplification factors corresponding to said second predetermined ratio. 12. A broad band directional coupling circuit as recited in claim 11 wherein said first and second shunt impedances are each comprised of two series impedances, the junctions of said two series impedances each defining third and fourth nodes, respectively, and wherein said first isolation means comprises first and second voltage to current amplifiers, the output of said first amplifier being connected to said first node and the output of said second amplifier being connected to said fourth node, and said second isolation means comprises third and fourth voltage to current amplifiers, the output of said third amplifier being connected to said second node and the output of said fourth amplifier being connected to said third node. 13. A broad band directional coupling circuit as recited in claim 3 wherein said attenuator network is a T attenuator network having a shunt impedance and first and second series impedances connected to a common node, said first series impedance being additionally connected to said first node and said second series impedance being additionally connected to said second node. 14. A broad band directional coupling circuit as recited in claim 13 wherein said first isolation means provides differential amplification with a ratio of amplification factors corresponding to said first predetermined ratio, and said second isolation means provides differential amplification with a ratio of amplification factors corresponding to said second predetermined ratio. 15. A broad band directional coupling circuit as recited in claim 14 wherein said shunt impedance is comprised of two series impedances, the junctions of said two series impedances defining a third node, and wherein said first isolation means comprises a first push-pull amplifier having positive and negative outputs, the positive input of said first push-pull amplifier being connected to said first node and the negative output of said first push-pull amplifier being connected to said third node, and said second isolation means comprises a second push-pull amplifier having positive and negative outputs, the positive output of said second push-pull amplifier being connected to said second node and the negative output of said second push-pull amplifier being connected to said third node. 16. A broad band directional coupling circuit as recited in claim 15 wherein said attenuator network is symmetrical and said two series impedances have values R.sub.3A and R.sub.3B, defined by the following equations: ##EQU10## where R.sub.3 is the value of said shunt impedance and K is the attenuation factor of said attenuation network. 17. A broad band directional coupling circuit as recited in claim 3 wherein said attenuator network is an H attenuator network having first and second series impedances and third and fourth series impedances and a shunt impedance, said shunt impedance being connected at one end to a first common junction with said first and second series impedances and at the other end to a second common junction with said third and fourth series impedances, said first series impedance being additionally connected to said first node and said second series impedances being additionally connected to said second node. 18. A broad band directional coupling circuit as recited in claim 17 wherein said first isolation means provides differential amplification with a ratio of amplification factors corresponding to said first predetermined ratio, and said second isolation means provides differential amplification with a ratio of amplification factors corresponding to said second predetermined ratio. 19. A broad band directional coupling circuit as recited in claim 18 wherein said shunt impedance is comprised of two series impedances, the junctions of said two series impedances defining a third node, and wherein said first isolation means comprises first and second voltage to current converting amplifiers, the output of said first amplifier being connected to said first node and the output of said second amplifier being connected to said third node, and said second isolation means comprises third and fourth voltage to current converting amplifiers, the output of said third amplifier being connected to said second node and the output of said fourth amplifier being connected to said third node. Other info: Inventors: Stuckert, Paul E. (Katonah, NY, US) Application Number: 484032 Filing Date: 1974-06-28 Publication_date: 1976-01-27 Assignee: International Business Machines Corporation (Armonk, NY) Primary Class(es): 330/100 327/403, 333/100, 333/112 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Heyman, John S. Assistant Examiner: Davis, B. P. Attorney: Sughrue, Rothwell, Mion & Zinn |
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