Communications: radio wave antennas – Antennas – With vehicle
Reexamination Certificate
1999-02-11
2001-04-10
Lee, Benny T. (Department: 2817)
Communications: radio wave antennas
Antennas
With vehicle
C333S02400C, C343S859000
Reexamination Certificate
active
06215449
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to coupling systems and methods and more particularly to systems and methods for coupling antennas through an insulator.
BACKGROUND OF THE INVENTION
Antenna coupling systems and methods are widely used to couple an antenna to a receiver through an insulator. For example in mobile radiotelephone communications, a radiotelephone such as a cellular radiotelephone may be mounted in the interior of a vehicle. An antenna may be mounted on the exterior of the vehicle. Coupling systems and methods are used to couple the antenna to the radiotelephone through an insulator such as a window.
It will be understood by those having skill in the art that although the present application will describe the coupling of mobile radiotelephones to antennas through a vehicle window, the present invention may be applied to any radio transceiver and the insulator need not be limited to windows. Moreover, the present invention need not be used in a mobile environment but also may be used to couple an antenna outside a building to a transceiver inside a building through an insulator.
It is known to use a capacitive plate on either side of a window to capacitively couple high frequency signals through the window. See U.S. Pat. No. 4,621,243 to Harada entitled “Transmission Channel Coupler for Antenna”. This patent also describes the use of loop coils and helical resonators to transmit high frequencies through a window.
Multiple plates also may be used on either side of the window to capacitively couple signals therethrough. See for example, U.S. Pat. No. 2,829,367 to Rychlik entitled “Television Lead-In Coupler” and U.S. Pat. No. 4,764,773 to Larsen et al. entitled “Mobile Antenna and Through-the-Glass Impedance Matched Feed System”.
Finally, it is also known to provide a collinear radiator mounted on one surface of a dielectric such as the window of a vehicle and a tunable coupling circuit disposed internally of a conductive housing mounted on the opposite surface of the dielectric. See U.S. Pat. No. 839,662 to Hadzoglou entitled “Cellular Mobile Communication Antenna”.
In providing antenna coupling systems and methods, it generally is desirable to couple the antenna to the transceiver through the insulator with low insertion loss. For example, in satellite radiotelephones which may provide low link margins, it may be desirable to maintain insertion loss through the insulator of about 0.5 dB or less. Unfortunately, many conventional coupling systems produce an insertion loss of 2 dB or more.
Moreover, many high performance antennas employ two or more conductors rather than a single conductor. For example, a quadrifiler helix antenna may employ two or more conductors. Accordingly, it may be desirable to couple radio frequency signals via a coaxial cable from inside the insulator to a coaxial cable outside the insulator. In conclusion, notwithstanding the above described solutions, there continues to be a need for coaxial-to-coaxial coupling systems and methods that can provide high performance and low insertion loss.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide antenna coupling systems and methods that can provide low insertion loss across an insulator.
It is another object of the present invention to provide antenna coupling systems and methods that can couple coaxial cables through an insulator.
These and other objects are provided, according to the present invention by coaxial coupling systems and methods that couple a first coaxial cable that includes a first inner conductor and first shield conductor to a second coaxial cable that includes a second inner conductor and a second shield conductor, through an insulator that includes first and second insulator surfaces. A first center plate and a first surrounding plate are adapted for attachment to the first insulator surface such that the first surrounding plate surrounds the first center plate on the first insulator surface. The first center plate is electrically connected to the first inner conductor and the first surrounding plate is electrically connected to the first shield conductor. A second center plate and a second surrounding plate are adapted for attachment to the second insulator surface such that the second surrounding plate surrounds the second center plate on the second insulator surface, the first and second center plates are adjacent one another with the insulator therebetween and the first and second surrounding plates are adjacent one another with the insulator therebetween. The second center plate is electrically connected to the second inner conductor and the second surrounding plate is electrically connected to the second shield conductor.
It has been found according to the present invention, that coaxial coupling systems and methods as described above can allow communication signals to pass with low insertion loss, over a desired frequency range, between an antenna mounted outside a window and a radio transceiver mounted inside the window. Transmission takes place via a coaxial transmission line on each side of the window. Moreover, by allowing two or more conductors to be capacitively coupled. a “single port” or “multiport” circuit may be provided for high performance antennas.
In a preferred embodiment, the first and second center plates are first and second disks and the first and second surrounding plates are first and second rings. More preferably, the first and second rings are first and second continuous rings. Moreover, a first inductor is preferably electrically connected between the first center plate and the first surrounding plate and a second inductor is preferably electrically connected between the second center plate and the second surrounding plate. A pair of first pads may be included, a respective one of which is on the first center plate and on the first surrounding plate so that the first inductor is electrically connected between the pair of first pads. A pair of second pads also may be included, a respective one of which is on the second center plate and on the second surrounding plate so that the second inductor is electrically connected between the pair of second pads.
A preferred configuration of the present invention can provide reduced insertion loss over a wide band, while reducing unwanted stray couplings. In particular, the first inner conductor is electrically connected to the first center plate at a first position thereon and the first inductor is electrically connected to the first center plate at a second position that is remote from the first position. The second inner conductor is preferably electrically connected to the second center plate at a first position thereon and is preferably electrically connected to the second center plate at a second position that is remote from the first position.
More preferably, the first position on the first center plate is adjacent the second position on the second center plate and the second position on the first center plate is adjacent the first position on the first center plate. Even more preferably, the first shield conductor is electrically connected to the first surrounding plate at a first position thereon and the second shield conductor is electrically connected to the second surrounding plate at a second position thereon that is remote from the first position on the first surrounding plate.
Most preferably, the first shield conductor is also electrically connected to the first surrounding plate at a first position thereon and the second shield conductor is electrically connected to the second surrounding plate at a second position thereon that is opposite the first position on the first surrounding plate. Thus, the first and second coaxial cables preferably emerge from the coupling system in opposite directions to reduce unwanted parasitic coupling. The first and second inductors preferably also are located at opposite locations from one another to reduce mutual inductance.
In another preferred aspect of the invention, the first center plate and the first surro
Ericsson Inc.
Jones Stephen E.
Lee Benny T.
Myers Bigel & Sibley & Sajovec
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