Half-sawtooth microstrip directional coupler

摘要

A directional coupler includes a main arm and a branch arm. The main arm includes a first main sawtooth section, a second main sawtooth section and a main straight section coupled between the first and second main sawtooth sections. The branch arm includes a first branch sawtooth section and a second branch sawtooth section. The first branch sawtooth section includes a first side and a second side. The first side of the first branch sawtooth section is shaped to include a zig-zag edge and the second side of the first branch sawtooth section is shaped to include a non-straight edge. The second branch sawtooth section includes a first side and a second side, and the first side of the second branch sawtooth section is shaped to include a zig-zag edge. The zig-zag edge of the first side of the first branch sawtooth section is coupled to the first main sawtooth section, and the zig-zag edge of the first side of the second branch sawtooth section is coupled to the second main sawtooth section. In an alternative embodiment, a method to make a coupler includes steps of fabricating a coupler based on a first pattern, modifying the coupler, measuring a performance parameter of the coupler, and revising the first pattern to make a second pattern for use in making more couplers. The fabricated coupler includes a main arm and a branch arm. The main arm includes a first main sawtooth section, a second main sawtooth section and a main straight section coupled therebetween. The branch arm includes a first branch sawtooth section and a second branch sawtooth section. The first branch sawtooth section includes a first side and a second side wherein the first side of the first branch sawtooth section is shaped to include a zig-zag edge. The second branch sawtooth section includes a first side and a second side wherein the first side of the second branch sawtooth section is shaped to include a zig-zag edge. The zig-zag edge of the first side of the first branch sawtooth section is coupled to the first main sawtooth section, and the zig-zag edge of the first side of the second branch sawtooth section is coupled to the second main sawtooth section.