Low-Profile Wideband and High-Gain LTCC Patch Antenna Array for 60 GHz Applications

Abstract

This communication presents a low-profile wideband and high-gain patch antenna array using low-temperature cofired ceramics (LTCCs) fabrication technique for 60 GHz applications. A coupled feeding scheme is adopted so that the antenna achieves wide impedance bandwidth that covers the entire 60 GHz license-free band with a height of only 0.384 mm (four tape layers). The shorting via connecting the upper patch and ground achieves the function of a virtual ac ground plane of differential feeding. This enables the antenna element to achieve good radiation performances, including stable gain (variation less than 1 dB) and a symmetrical beam with low cross-polarization over the entire frequency band. The performances of the antenna element are comparable to that of the differential-driven patch antenna while the complex differential feeding network is not required. Furthermore, the proposed antenna element with simple and easy-to-integrate geometry is successfully extended to a $4 \times 4$ antenna array using a substrate integrated waveguide (SIW)-based feeding network. The measured results show that the impedance bandwidth of the array covers the 60 GHz license-free band. The maximum gain can reach 16.7 dBi and the radiation performances are very stable over the operating frequency band.