Microwave and millimeter wave switched-line type phase shifter including exponential line portion

Claim 1

An RF phase shifter comprising: a dielectric substrate; at least one RF signal port; a reference RF transmission line comprising a first elongated conductor disposed on a first major surface of said substrate and having a reference phase length, said reference transmission line having a reference phase change versus frequency characteristic; an alternate RF transmission line comprising a second elongated conductor disposed on a second major surface of said substrate and having an alternate phase length different from said reference phase length, said alternate transmission line including as a portion thereof, a coupled exponential transmission line comprising a segment of said second conductor, said segment having first and second ends disposed adjacent to each other and first and second halves extending substantially parallel from said first and second ends, respectively, to a common connection between them, said halves being spaced apart along their lengths by a separation distance, said coupled exponential transmission line having a continuous narrowing taper along its length from said first and second ends of said conductor segment to said common connection, the length of said halves, their separation distance, their width and said continuous narrowing taper together being tailored to provide said alternate RF transmission line with an alternate phase change versus frequency characteristic over an operating frequency range which is substantially the same as said reference phase change versus frequency characteristic; and means coupled between said at least one RF signal port and said reference and alternate transmission lines for selectively connecting either said reference transmission line or said alternate transmission line to said at least one RF signal port to select the one of said reference and alternate transmission lines which is connected to said at least one RF signal port as the existing RF signal transmission path through said phase shifter.