COMPOSITE RIGHT/LEFT (CRLH) COUPLERS

• US 20120139659A1
• Filed: 12/06/2011
• Published: 06/07/2012
• Est. Priority Date: 03/26/2004
• Status: Active Grant

• Current Assignee: California Polytechnic State University (California State University System), Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Itoh, Tatsuo, Caloz, Christophe, Lin, I-Hsiang, Okabe, Hiroshi
• Granted Patent: US 8,405,469 B2
• Time in Patent Office: Days
• US Class Current: 333/100
• CPC Class Codes: H01P 5/227 90° branch line couplers

Abstract

High-frequency couplers and coupling techniques are described utilizing artificial composite right/left-handed transmission line (CRLH-TL). Three specific forms of couplers are described; (1) a coupled-line backward coupler is described with arbitrary tight/loose coupling and broad bandwidth; (2) a compact enhanced-bandwidth hybrid ring coupler is described with increased bandwidth and decreased size; and (3) a dual-band branch-line coupler that is not limited to a harmonic relation between the bands. These variations are preferably implemented in a microstrip fabrication process and may use lumped-element components. The couplers and coupling techniques are directed at increasing the utility while decreasing the size of high-frequency couplers, and are suitable for use with separate coupler or couplers integrated within integrated devices.

Claims

1. A coupler apparatus for generating separate signal channels from a radio-frequency input, comprising:

an input line configured for receiving a high-frequency input signal;

a transmission line connecting said input line to an output line and to at least one separate signal channel; and

means for creating a left-handed anti-parallel relationship between phase and group velocities below a transition frequency, ω

₀, and a right-handed parallel relationship between phase and group velocities above transition frequency ω

₀, within at least a portion of said transmission line, to generate backward wave coupling;

wherein said means comprises an artificial composite right/left-handed (CRLH) transmission line (TL);

wherein said CRLH TL comprises a unit cell;

wherein said unit cell comprises a series combination of a right-handed inductor and a left-handed capacitor; and

wherein said series combination of said right-handed inductor and said left-handed capacitor is coupled to a paralleled combination of a right-handed shunt capacitor and a left-handed shunt inductor.