The invention discloses a combined antenna for a
millimeter wave automobile
radar. The combined antenna is composed of three
layers of
dielectric materials and four
layers of
metal. The
metal layer comprises a
radiation layer, an antenna reflection layer, a strip line feed layer and a bottom floor layer. The
radiation layer is etched with more than two identical grid
radiation units which are arranged at equal intervals, and non-radiation edges of the grid units are bent arcs instead of traditional straight lines. The radiation edge replaces a traditional same-width
microstrip line with a gradually-changed
microstrip line, and the length and width of the connecting section between the units are consistent with those of the radiation edge of the grid unit, so that the design difficulty of the antenna is reduced. The patch units are added in the blank areas in the middle of the grid units and are connected with the non-radiation edges of the grids through the
microstrip lines, and the patch units and the connecting sections between the units form a series
patch antenna, so that the area of the antenna is effectively utilized. Because the area in the middle of the grid unit is small, the frequency of the resonant mode generated by the
patch antenna is slightly higher than that of the grid antenna, the radiation units in two forms form a combined
antenna effect, and the working bandwidth of the antenna is widened by the radiation of the generated two groups of resonant
modes. The antenna adopts a via hole for feeding, feeding points are bilaterally symmetrical about the center of the
linear array, and the via hole penetrates through a through hole in the antenna reflection
ground layer and is connected with the strip line feeding layer; the strip line feed layer comprises a T-shaped power divider and a phase shifter realized by using an additional length, and is used for realizing differential feed. The antenna is simple in structure, easy to design, low in cost and suitable for
millimeter wave band automobile radars.