Tilted-Beam High Gain Antenna System Composed of a Patch Antenna and Periodically Arrayed Loops

A fed patch antenna is printed on a dielectric substrate (substrate 1) and a parasitic dielectric substrate (substrate 2) is located above the patch. Parasitic substrate 2 has M × (2N-1) strip loops on its bottom layer. The strip loops are square and specified by a fixed outer side length of s_out and inner side lengths s_m(m=1, 2,..., M). When all the inner side lengths are equal, a high gain beam is formed in the direction normal to substrate 2. This normal beam is tilted by changing the phase distribution of the electric field over a horizontal plane just above substrate 2. It is found that gradating the strip widths of the loops contributes to changing the phase distribution, forming a high-gain tilted beam. A system of M × (2N - 1) = 9 × 9 shows an experimental maximum gain of 16.4 dBi for a 33° beam tilt. The frequency responses for the radiation pattern, beam direction, and VSWR for this high-gain antenna are also discussed.