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US 4,882,553 AGranted
Microwave balun
AssigneeU.S. Philips Corporation
InventorsRobert Davies, Percy W. Hoare, Peter J. Gibson
Life of this patent
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AssigneeU.S. Philips Corporation
InventorsRobert Davies, Percy W. Hoare, Peter J. Gibson
Estimating the term…
A broadband balun, suitable for feeding a spiral antenna, has a balanced port (20) comprising two adjacent strip conductors (16,17; 36,37) which are coupled to the unbalanced port (6) by respective paths of the same effective electrical lengths. The paths comprise respective strip transmission lines (9,10) having a common ground conductor (3; 44) which terminates in a transition to the balanced line (19), and further comprise slot line means (11; 21) and strip transmission line-to-slot line coupling means (14,15) so arranged as in operation to provide in the two strip conductors (16,17; 36,37) from an RF signal at the unbalanced port (6) signals of mutually opposite phases with respect to the common ground conductor (3; 44). The two strip conductors (16,17) may be disposed on the outer surfaces of two substrates (1,2) with a ground plane (3) between the substrates, or may be coplanar (36,37) with a transition to an unbalanced line comprising strip conductors (45, 46) on opposite sides of a central ground conductor (44) in the same plane.
A balun having an unbalanced port comprising a first unbalanced transmission line and a balanced port comprising a balanced transmission line formed by two adjacent elongate strip conductors of substantially the same widths between which in operation of substantially the same widths between which in operation an electric field extends, wherein the two strip conductors are coupled to the unbalanced port by respective paths of substantially the same effective electrical lengths, wherein the paths comprise adjacent respective further unbalanced transmission lines which are strip transmission lines having a common ground conductor, wherein there is a transition from the adjacent unbalanced lines to said balanced line in which transition the common ground conductor terminates, and wherein at least one of the paths comprise slot line means and strip transmission line-to-slot line coupling means so arranged. as in operation to provide in the two strip conductors from an RF signal in the first unbalanced line RF signals of mutually opposite phases with respect to the common ground conductor.
Dependencies are inferred from the claim text.