To easily produce a microstrip antenna in a simple constitution to partly deform a loop-shaped circuit to easily approximate another loop-shaped circuit, etc., to the deformed circuit and also by preparing a feeder line and a matching line.

An antenna element 2 consists of a metallic film which is adhered to a loop-shaped circuit on the surface of a dielectric plate 1 having small thickness compared with the radiation wavelength. Then the loop-shaped circuit is partly deformed without changing substantially the electrical characteristic of the element 2. When the plate 1 uses a glass cloth base fluororesin copper-plated laminate, the unnecessary metallic films are eliminated by the same method as a print method and the element 2, a feeder line 3 and the loop deformation parts 41 to 44 are adhered on the surface of the plate 1. Thus another antenna element can be added without changing substantially the proper characteristic impedance, the resonance wavelength, the directional pattern, etc., of a microstrip antenna.