Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
1999-05-19
2001-02-27
Gensler, Paul (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C370S278000, C455S079000, C455S103000
Reexamination Certificate
active
06194980
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to radio frequency (RF) communications systems and specifically to multiple RF communications systems collocated on airborne, marine, or ground platforms.
Present airborne, marine, or ground platforms with three or more collocated RF communications systems utilize one or more antennas for each system. Multiple antennas require space in short supply on most platforms, increase drag on aircraft, present unwanted unique platform signatures both visibly and on radar, and interact with each other to distort radiation patterns and degrade communications system performance. All platform users desire to reduce the number of antennas on the platform.
Present systems and methods used to reduce the number of antennas have many deficiencies. One type of system, referred to as a multicoupler, employs agile high power filters for the transmitters and preselectors for the receivers. Also used are signal cancellation techniques. These systems are high cost, large in physical size, have high losses of RF energy, offer poor isolation between ports, have interaction between circuit elements causing producibility and maintenance problems.
SUMMARY OF THE INVENTION
A hybrid radio frequency (RF) combining system for combining RF source outputs into a radio frequency combining system output is disclosed. Three or more quadrature hybrid couplers are connected in a series arrangement. Each coupler in the series has an output port, a first input port, a second input port, and an isolation port. The first coupler in the series of quadrature hybrid couplers has the first input port connected to a first RF source, the second input port connected a load, the isolation port connected to a first short, and the output port connected to the input port of the next quadrature hybrid coupler the series. The last coupler in the series of quadrature hybrid couplers has the first input port connected to the output port of a previous coupler in the series, the second input port connected to the last RF source, the isolation port connected to the last short, and the output port forms the radio frequency combing system output. An interim coupler in the series has the first input port connected to the output port of a previous coupler, the second input port connected to an interim RF source, the isolation port connected to an interim short, and the output port connected to the input port of the next quadrature hybrid coupler in the series. The RF combining system combines the outputs of several transmitters into one antenna. The present invention can also be used in a receive mode to combine the output of a receive antenna with outputs from a receiver interference canceller. The output of the combining system is then passed to a multiple receiver system.
It is an object of the present invention to provide an RF combining system that allows for the reduction in the number of antennas on platforms with multiple communications systems and is expandable to add RF sources as needed.
It is another object of the present invention to provide an RF combining system that is small in size, low cost, reduces RF losses, offers good isolation, and is easy to produce and maintain.
It is an advantage of the present invention to use commonly available 90 degree RF hybrid couplers configured in a unique manner.
It is an advantage of the present invention to provide an RF combining system that is a low loss coupler system without complex circuit elements and with excellent isolation between ports.
It is a feature of the present invention to be able to use the RF combining system in both transmit and receive applications.
These and other objects, features, and advantages are disclosed and claimed in the specification, figures, and claims of the present application.
REFERENCES:
patent: 3619504 (1971-11-01), DeVeer et al.
patent: 4423392 (1983-12-01), Wolfson
patent: 4633202 (1986-12-01), Basile et al.
patent: 5630223 (1997-05-01), Bahu et al.
Eppele Kyle
Gensler Paul
Jensen Nathan O.
O'Shaughnessy James P.
Rockwell Collins, Inc.
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