Microstrip patch antenna and array antenna using supertrate

A microstrip array antenna having a plurality of microstrip patch antennas, each of the microstrip patch antenna comprising:

• a lower patch antenna layer having a dielectric layer and a ground plane, for radiating energy by exciting current by a feeding means electrically connected to a lower radiating patch on a side of the dielectric layer;
• an upper patch antenna layer having a dielectric film, for radiating energy by exciting current by the lower radiating patch electromagnetically connected to an upper radiating patch on a side of the dielectric film;
• a foam layer for distancing the upper patch antenna layer from the lower patch antenna layer by arranging the foam layer between the lower patch antenna layer and the upper patch antenna layer;
• and
• a dielectric superstrate located with a predeteremined distance from the upper patch antenna layer,
• wherein the microstrip array antenna is designed using a corporate feeding method and an element spacing of the microstrip patch antennas is more than λ0 at 12 GHz to minimize the coupling between the microstip patch antennas, wherein although the element spacing in the array is wider than the wavelength at 12 GHz in free space, the grating lobes can be reduced by the dielectric superstrate.