Multiport radio frequency signal combiner

• US 4,375,622 A
• Filed: 04/20/1981
• Issued: 03/01/1983
• Est. Priority Date: 04/20/1981
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Hollingsworth, Allen H., Deutschle, Alan G.
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US06/255,408
• Time in Patent Office: 680 Days
• Field of Search: 333/101, 333/104, 333/105, 333/120, 333/126, 333/127, 333/129, 333/134, 333/136, 333/263, 333/128, 370/38, 455/103
• US Class Current: 333/126
• CPC Class Codes: H01P 1/213 combining or separating two or more different frequencies H01P1/215 takes precedence
• CPC Class Codes: H01P 5/12 Coupling devices having more than two ports H01P5/04 takes precedence

Abstract

A multiport radio frequency (RF) signal combiner is described for combining three or more RF signals for application to an antenna. The combiner includes an input port for each RF signal, an output port coupled to the antenna, and a tuning port coupled to a tuning transmission line. The input ports, output port and tuning port are connected to a terminating element. The tuning transmission line is terminated by a fixed or adjustable short-circuit impedance for substantially eliminating the capacitive discontinuity created by interconnecting the input ports. The RF signal combiner can be advantageously utilized in any radio system where it is necessary to multiplex the RF signals from three or more transmitters to a single antenna.

Claims

1. Apparatus for combining at least three radio frequency signals, having different predetermined frequencies and being generated by separate signal sources, to provide a composite output signal, comprising:

a plurality of input transmission line means each having a signal conductor and a predetermined characteristic impedance, disposed in the same plane with one another and coupled to a corresponding one of the radio frequency signals;

output transmission line means having a signal conductor and a predetermined characteristic impedance and providing the composite output signal;

a terminating element for commonly interconnecting at substantially a single point the signal conductors of the input transmission line means and the signal conductor of the output transmission line means and combining the radio frequency signals on the signal conductors of the input transmission line means to provide the composite output signal on the signal conductor of the output transmission line means, each of the signal conductors of the input transmission line means radially connected to the terminating element, and the signal conductor of the output transmission line means disposed perpendicular to the plane of the signal conductors of the input transmission line means; and

tuning transmission line means having a signal conductor and a predetermined characteristic impedance and being terminated by a predetermined impedance, the signal conductor of the tuning transmission line means connected to the terminating element substantially at the single interconnection point for substantially eliminating the effects of the capacitive discontinuity created at the interconnection point.

2. The combining apparatus according to claim 1, wherein the tuning transmission line means is terminated by a short-circuit impedance.

3. The combining apparatus according to claim 1, wherein the tuning transmission line means is terminated by an open-circuit impedance.

4. The combining apparatus according to claim 1, wherein said tuning transmission line means is disposed in the same plane as the input transmission line means.

5. The combining apparatus according to claim 1, wherein the tuning transmission line means is disposed perpendicular to the plane of the input transmission line means.

6. The combining apparatus according to claim 1, wherein the terminating element has a cylindrical shape and is comprised of an electrically conductive material.

7. The combining apparatus according to claim 1, wherein the terminating element has a circular shape and is comprised of an electrically conductive material.

8. The combining apparatus according to claim 4, wherein the terminating element has a cylindrical shape and is comprised of an electrically conductive material, the cylindrically shaped terminating element having parallel top and bottom surfaces and a radial surface, the plurality of input and the tuning transmission line means connected to the radial surface of the cylindrical terminating element, and the output transmission line means coupled to one of the top and bottom surfaces.

9. The combining apparatus according to claim 5, wherein the terminating element has a cylindrical shape and is comprised of an electrically conductive material.

10. The combining apparatus according to claim 9, wherein the cylindrically shaped terminating element has parallel top and bottom surfaces and a radial surface, the plurality of input transmission line means each connected to the radial surface, the output transmission line means connected to one of the top and bottom surfaces, and the tuning transmission line means connected to the surface opposite said one of the top and bottom surfaces.

11. The combining apparatus according to claim 9, wherein the output transmission line means, tuning transmission line means and terminating element are integrally comprised of an electrically conductive material.

12. Apparatus for combining at least three radio frequency signals, having different predetermined frequencies, to provide a composite output signal, comprising:

a plurality of transmitting means each for generating a radio frequency signal having a predetermined frequency;

a plurality of filtering means each coupled to one of the transmitting means for filtering the radio frequency signal therefrom;

a plurality of input transmission line means each having a signal conductor and a predetermined characteristic impedance, disposed in the same plane with one another and coupled to one of the filtered radio frequency signals from the filtering means;

output transmission line means having a signal conductor and a predetermined characteristic impedance and providing the composite output signal;

PG,15

a terminating element for commonly terminating at substantially a single point the signal conductors of the input transmission line means and the signal conductor of the output transmission line means and combining the radio frequency signals on the signal conductors of the input transmission line means to provide the composite output signal on the signal conductor of the output transmission line means, each of the signal conductors of the input transmission line means radially connected to the terminating element, and the signal conductor of the output transmission line means disposed perpendicular to the plane of the signal conductors of the input transmission line means; and

tuning transmission line means having a signal conductor and a predetermined characteristic impedance and being terminated by a predetermined impedance, the signal conductor of the tuning transmission line means connected to the terminating element substantially at the single interconnection point for substantially eliminating the effects of the capacitive discontinuity created at the interconnection point.

13. The combining apparatus according to claim 12, wherein the tuning transmission line means is terminated by a short-circuit impedance.

14. The combining apparatus according to claim 12, wherein the tuning transmission line means is terminated by an open-circuit impedance.

15. The combining appartus according to claim 12, wherein said tuning transmission line means is disposed in the same plane as the input transmission line means.

16. The combining apparatus according to claim 12, wherein the tuning transmission line means is disposed perpendicular to the plane of the input transmission line means.

17. The combining apparatus according to claim 12, wherein the terminating element has a cylindrical shape and is comprised of an electrically conductive material.

18. The combining apparatus according to claim 12, wherein the terminating element has a circular shape and is comprised of an electrically conductive material.

19. The combining apparatus according to claim 15, wherein the terminating element has a cylindrical shape and is comprised of an electrically conductive material, the cylindrically shaped terminating element having parallel top and bottom surfaces and a radial surface, the plurality of input and the tuning tranmission line means connected to the radial surface of the cylindrical terminating element, and the output transmission line means coupled to one of the top and bottom surfaces.

20. The combining apparatus according to claim 16, wherein the terminating element has a cylindrical shape and is comprised of an electrically conductive material.

21. The combining apparatus according to claim 20, wherein the cylindrically shaped terminating element has parallel top and bottom surface and a radial surface, the plurality of input transmission line means each connected to the radial surface, the output transmission line means connected to one of the top and bottom surfaces, and the tuning transmission line means connected to the surface opposite said one of the top and bottom surfaces.

22. The combining apparatus according to claim 20, wherein the output transmission line means, tuning transmission line means and terminating element are integrally comprised of an electrically conductive material.

23. The combining apparatus according to claim 12, further including antenna means coupled to the output transmission line means for radiating the composite signal.