Wave transmission lines and networks – Coupling networks – Delay lines including long line elements
Reexamination Certificate
1999-05-13
2001-03-27
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
Delay lines including long line elements
C333S156000
Reexamination Certificate
active
06208222
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to microstrip microwave transmission lines and, more particularly, to a transmission line phase shifter which is effective, inexpensive and easy to fabricate.
There are numerous applications where a microstrip microwave transmission line is required to have a phase shifter inserted therein. For example, phase shifters are commonly used in phased array antenna systems. At the present time, electromechanical phase shifters exist which require a quadrature hybrid circuit so that a signal passes through the quadrature hybrid circuit and bounces off a variable length delay line. The bounced signal then returns through the isolated port of the quadrature hybrid circuit. Such a device operates in a reflective mode, which limits the operating bandwidth and adds complexity and cost to the design. Line stretchers are also known to exist which allow for a continuously variable phase shift using transmission, rather than reflection. However, line stretchers require more expensive hardware since they are typically telescoping coaxial structures. Accordingly, a need exists for a less expensive phase shifter.
SUMMARY OF THE INVENTION
The inventive phase shifter is designed for use over a frequency band having a center frequency and includes a conductive base plate and a pair of microstrip transmission line segments supported parallel to each other and parallel to and spaced from the base plate. A movable microstrip transmission line bridges the pair of transmission line segments and is movable therealong to provide a short circuit therebetween. A movable ground element is coupled to the movable transmission line for movement therewith and is in contact with the pair of transmission line segments and the base plate. The spacing between the movable transmission line and the ground element is maintained at one quarter wavelength at the center frequency.
REFERENCES:
patent: 5473294 (1995-12-01), Mizzoni et al.
patent: 46606 (1985-03-01), None
patent: 242001 (1988-10-01), None
Davis David L.
Lee Benny
Lucent Technologies - Inc.
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