RF impedance selector and/or RF short switch

Details RF impedance selector and/or RF short switch RF impedance selector and/or RF short switch

1999-10-15

2002-05-21

Lee, Benny (Department: 2817)

Wave transmission lines and networks

Long line elements and components

Including variable impedance

C333S033000

Reexamination Certificate

active

06392511

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to coaxial cable transmission lines. It finds particular application in conjunction with impedance matching coaxial cable transmission lines, and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other like applications.
Coaxial cables are known to comprise an inner conductor, a dielectric material, and an outer conductor. The outer conductor comprises a conductive material that encircles both the inner conductor and dielectric material. Electrically, the outer conductor shields the inner conductor that is carrying an electrical signal. In this manner, electromagnetic interference (EMI) radiated from the coaxial cable is minimized. The dielectric material, which encircles the inner conductor, electrically isolates the inner conductor from the outer conductor. The dielectric material is selected based on the characteristic impedance desired for the coaxial cable.
As is also known, coaxial cables are used to electrically couple high frequency signals from one circuit to another. Care should be taken when coupling RF coaxial wires to ensure that the characteristic impedances of the members to be connected are substantially matched. Coaxial cables having substantially matched impedances limit losses resulting from reflections and the like.
Coaxial connectors provided with means for impedance control or matching are known in the art. In order to achieve a desired impedance, use is made of passive electronic components such as resistors, coils, and capacitors, which are typically included in the connector casing. These components take up relatively large amounts of space, which has an adverse effect on the dimensions of the connectors. Furthermore, it is disadvantageous from an assembly point of view to mount separate resistors, coils and the like in a connector casing and electrically connect those components to the contact members in question.
A need exists for an RF selector that allows a user to selectively change the characteristic impedance of a coaxial cable without the use of impedance controlling coaxial connectors.
The present invention provides a new and improved apparatus and method which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
An impedance selector includes an input port receiving input signals. An outer conductor electrically communicates with the input port. A dielectric material is encircled by the outer conductor. An inner conductive core is encircled by the outer conductor and electrically communicates with the input port. An output port electrically communicates with the input port via the outer conductor and the inner core. A characteristic impedance of the outer conductor and the inner core is selectively set as a function of a minimum distance between the inner core and the outer conductor.
In accordance with one aspect of the invention, a rotation device non-concentrically encircles the outer conductor. The outer conductor moves in a fixed relationship with respect to the rotation device. The minimum distance changes as a function of selected rotational positions of the rotation device.
In accordance with another aspect of the invention, at least one additional outer conductor electrically communicates with the input and output ports. Each of the outer conductors has a distinct respective diameter and encircles independent portions of the dielectric material. The inner conductive core is encircled by a selected one of the outer conductors. The minimum distance is defined as a function of the selected outer conductor encircling the inner core.
Another advantage of the present invention is that an impedance can be selectively set to provide an impedance matching between an input and an output port.
Another advantage of the present invention is that the impedance selector is a less expensive alternative to conventional RF switches.
Another advantage of the present invention is that the impedance selector provides less insertion loss than conventional switches.
Another advantage of the present invention is that the impedance selector requires less hardware than conventional designs.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.


REFERENCES:
patent: 5545949 (1996-08-01), Bacher

Affiliated with

Also associated with

Rating

RF impedance selector and/or RF short switch does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with RF impedance selector and/or RF short switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and RF impedance selector and/or RF short switch will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2844697