Electromagnetic band-gap based corrugated structures for reducing mutual coupling of compact 60 GHz cavity-backed antenna arrays in low temperature co-fired ceramics

Reducing the mutual coupling of antenna elements in 60 GHz phased arrays is an important issue because it directly affects the input impedance matching and radiation performances. This study presents an electromagnetic band-gap (EBG) based design using corrugated structures to reduce the mutual coupling between two closely placed antenna elements. An isolation enhancement of 3.6 to 10.3 dB was achieved from the proposed EBG-based corrugated structure over the unlicensed band of 57 to 66 GHz. Based on the available thickness of low temperature co-fired ceramics (LTCC) layered process, the authors built a prototype with a corrugation height of 0.7 mm and measured the port isolation and radiation performances. The experimental results show that using the corrugated design may reduce the mutual coupling by 2.1 to 4.4 dB compared with that without corrugation. In addition, the corrugated design under the thickness restriction of the LTCC process is discussed in this study. An alternative structure with an extended corrugation height is included, where the port isolation is improved by more than 3 dB over the entire band of 57 to 66 GHz.