Multilayer 180° hybrid coupler in LTCC technology for 24GHz applications

This paper presents a new 180° hybrid coupler realized in multilayer LTCC technology. Proposed coupler has non-interspersed inputs/outputs, reduced size compared to conventional rat race hybrid and is robust to LTCC layer misalignment. Non-interspersed property can ease laying out complex microwave circuits compared to the use of a conventional microstrip hybrid coupler and recently introduced coupler with edge coupled lines. It was achieved by re-wiring edge coupled hybrid and implementing broad side coupled lines in multilayer substrate. Coupler design is demonstrated for 24GHz application. Measured characteristics are in good agreement with simulations and show very good performance of the proposed coupler.