60-GHz Thin Broadband High-Gain LTCC Metamaterial-Mushroom Antenna Array

A low-profile broadband metamaterial-mushroom antenna array is proposed for high-gain 60-GHz band applications. The antenna array consists of a single-layer mushroom radiating structure and a simplified single-layer substrate integrated waveguide (SIW) feeding network. A new transmission-line based model is presented to estimate the resonant frequencies of the operating TM10 and antiphase TM20 modes. With the metamaterial-mushroom structure, the closely-placed antenna elements realize less mutual couplings, higher aperture illumination efficiency compared to conventional patch antennas. An 8 × 8 mushroom antenna array is designed and prototyped using low-temperature cofired ceramic (LTCC), the measurement shows the antenna array with the feeding transition proposed an impedance bandwidth of 56.3-65.7 GHz with a boresight gain greater than 21.2 dBi and up to 24.2 dBi at 62.3 GHz. The proposed antenna array features the merits of high gain, broadband, compact size, and low cross-polarization levels.