Microstrip antenna structure and microwave imaging system using microstrip antenna structure

The invention discloses a microstrip antenna structure and a microwave imaging system using the microstrip antenna structure. The microstrip antenna structure includes a substrate, a ring-shaped microstrip structure, and a signal transmission port. The substrate has first and second surfaces opposite to each other. A ring-shaped microstrip structure is disposed on the first surface of the substrate and is used for forming a radiating band. The signal transmission port is disposed on the second surface of the substrate, penetrates the substrate, and is electrically connected to the ring-shapedmicrostrip structure. The difference between the half-power bandwidth in afirst vertical plane and the half-power bandwidth in a second vertical plane of an electric field generated by the ring-shapedmicrostrip structure is less than 5 degrees, wherein the first vertical plane and the second vertical plane are perpendicular to the main planes of the microstrip antenna structure. The invention cansolve the problem of unequ