Low-Profile Artificial Grid Dielectric Resonator Antenna Arrays for mm-Wave Applications

Wideband artificial grid dielectric resonator antenna (GDRA) arrays at 32 GHz for mm-wave applications are presented. The antenna array comprised a GDRA layer and a substrate-integrated waveguide feeding layer. The GDRA array layer is built by embedding small rectangular metal grid structures in low-permittivity dielectric polymethyl methacrylate (PMMA) using deep X-ray lithography (DXRL) and electroforming. The rectangular metallic inclusions significantly increase the effective permittivity of the base material up to 17 by creating high electric flux density regions inside. Low-loss substrate-integrated waveguide (SIW) feeding with longitudinal slots is utilized to excite the GDRA array layer. A 200~\mu \text{m} -thin perforated layer of PMMA is applied between the rectangular grid structures and the SIW feedlines to avoid shorting the metal inclusions to the excitation slots while improving broadband energy coupling to the GDRA layer. The size of the single GDRA array element is only 2.7 mm \times2.7 mm \times0.5 mm ( 0.29\lambda _{\mathrm {o}}\times 0.29\lambda _{\mathrm {o}}\times 0.05\lambda _{\mathrm {o}} ). Four-element ( 1 \times 4 ) and eight-element ( 1 \times 8 ) GDRA arrays have been fabricated and measured. A measured impedance bandwidth of 6 GHz with a broadside peak gain of 12 dBi and 76% measured radiation efficiency is obtained at 32 GHz for the 1 \times 8 GDRA array.