60-GHz LTCC Miniaturized Substrate Integrated Multibeam Array Antenna With Multiple Polarizations

In this paper, miniaturized substrate integrated multibeam array antennas are proposed and designed at 60 GHz. Owing to the design flexibility of the low temperature cofired ceramic (LTCC) technology, the entire multibeam antenna size is only equal to the size of radiating aperture by carefully embedding the complicated substrate integrated waveguide (SIW) feeding network underneath the radiating array. After introducing design procedures for the folded Butler matrix and the corresponding radiating array, a ± 45^° dual linear-polarization (LP) and a dual circular-polarization (CP) substrate integrated multibeam array antennas are designed and fabricated, respectively. Here, each multibeam antenna has four switchable beams with different pointing directions. Each beam direction has two orthogonal LP or CP modes, therefore allowing the polarization diversity. Measured results validate our design and demonstrate good performances of our proposed structures.