Patent ID: 7750853

Claim:
A microstrip antenna adapted for use on a missile comprising: (a) first, second and third rectangular shaped 120-degree microstrip antenna elements mounted on an outer surface of said missile adjacent to one another, each of said first, second and third 120-degree microstrip antenna elements including: (i) a first dielectric layer operating as a protective layer for each of said 120-degree microstrip antenna elements; (ii) a second dielectric layer positioned below said first dielectric layer within each of said 120-degree microstrip antenna elements, said second dielectric layer having an upper surface and a lower surface; (iii) a rectangular shaped copper radiating element mounted on the upper surface of said second dielectric layer; (iv) a rectangular shaped ground plane mounted on the lower surface of said second dielectric layer; (v) a plurality of equally spaced apart aligned copper vias passing through a plurality of openings located in said second dielectric layer, wherein said plurality of vias are located near one edge of said radiating element from a midpoint of said radiating element extending to a corner of said radiating element; (vi) said plurality of vias connecting said radiating element to the ground plane of each of said first, second and third rectangular shaped 120-degree microstrip antenna elements to form a partial short circuit from said radiating element to said ground plane; and (vii) a tuning screw positioned within said second dielectric substrate and said ground plane at a corner of said ground plane which is diagonally opposite the corner of said radiating element which includes one of said plurality of vias; (b) said first, second and third 120-degree microstrip antenna elements generating a radiation pattern which includes horizontal polarization and vertical polarization with cross polarization at an operating frequency for said microstrip antenna of 231 MHz; and (c) said partial short circuit providing for a current flow pattern through said radiating element and said plurality vias to said ground plane for each of said first, second and third 120-degree microstrip antenna elements which allows for a substantial increase in the bandwidth of said microstrip antenna to ±400 KHz about the operating frequency for said microstrip antenna of 231 MHz.