Extended bandwidth microstrip antenna

A microstrip antenna having approximately an octave bandwidth comprises a planar radiating element disposed approximately coplanar with and in front of an upper ground plane and spaced above a lower ground plane at a distance equal to approximately one-tenth wavelength at the lowest operating frequency (one-quarter wavelength at the upper operating frequency). A thin dielectric layer is disposed on top of the upper ground plane which is coupled to the lower ground plane. The antenna, which is linearly polarized, is fed from the rear by a launcher that is approximately coplanar with the radiating element and mounted above the dielectric layer. Impedance matching means are provided for improved performance.