Gain-Enhanced 60-GHz LTCC Antenna Array With Open Air Cavities

The gain of low temperature co-fired ceramic (LTCC) patch antenna arrays operating at 60 GHz is enhanced by introducing open air cavities around their radiating patches. The open air cavities reduce the losses caused by severe surface waves and dielectric substrate at millimeter-wave (mmW) bands. The arrays are excited through either a microstrip-line or stripline feed network with a grounded coplanar-waveguide (GCPW) transition. The GCPW transition is designed so that the antenna can be measured with the patch array facing free space therefore reducing the effect of the probe station on the measurement. The proposed antenna arrays with the open air cavities achieves gain enhancement of 1–2 dB compared to the conventional antenna array without any open air cavity across the impedance bandwidth of about 7 GHz for
$\vert S_{11}\vert \leq - 10$
dB at 60-GHz band.