Reduction of mutual coupling for compact 60-GHz cavity-backed antennas in LTCC

Reducing the mutual coupling of antenna elements in 60-GHz phased arrays is an important issue because it directly affects the port impedance and radiation patterns. This paper presents an EBG-based design using corrugated structures to reduce the mutual coupling between two antenna elements with an edge-to-edge distance of 1.65 mm (0.33λ₀). Isolation enhancement using the corrugated structure with a height of 0.65 mm is up to 10.3 dB in simulation and is assured over the frequency of 57 to 66 GHz. Limited to the LTCC process with each layer of 0.1 mm height, the prototype of a corrugation height of 0.7 mm is chosen to verify the isolation enhancement and the agreed experimented and simulated results are shown.