60-GHz $2 \times 2$ LTCC Patch Antenna Array With an Integrated EBG Structure for Gain Enhancement

This letter presents a 60-GHz 2 × 2 low temperature co-fired ceramic (LTCC) aperture-coupled patch antenna array with an integrated Sievenpiper electromagnetic band-gap (EBG) structure used to suppress TM-mode surface waves. The merit of this EBG structure is to yield a predicted 4-dB enhancement in broadside directivity and gain, and an 8-dB improvement in sidelobe level. The novelty of this antenna lies in the combination of a relatively new LTCC material system (DuPont Greentape 9K7) along with laser ablation processing for fine line and fine slot definition (50-μm gaps with +/ - 6 μm tolerance) allowing the first successful integration of a Sievenpiper EBG structure with a millimeter-wave LTCC patch array. A measured broadside gain/directivity of 11.5/14 dBi at 60 GHz is achieved with an aperture footprint of only 350 × 410 mil
²
(1.78λ × 2.08λ) including the EBG structure. This thin (27 mil) LTCC array is well suited for chip-scale package applications.