Dual band dual linear polarization elliptical microstrip ring antenna

An analysis is presented for an aperture coupled microstrip elliptical ring antenna. The results demonstrate that the antenna has a dual resonance and the separation between resonances is controlled by the eccentricity of the ring. The antenna is excited by two independent perpendicular microstrip feeds parallel to the minor and major axis of the elliptical ring and which are located on a dielectric slab below the common ground plane. The orthogonality of the feeds creates two orthogonal linear polarized radiated fields. Theory demonstrates resonant frequencies from 12.0 GHz to 16.5 GHz, VSWR<2, bandwidth of 6%, and isolation of 15-30 dB. The antenna radiates a single main beam with a 3 dB beamwidth of 90/spl deg/ and cross-polarization greater than 30 dB. The elliptical ring antenna is small (D//spl lambda//sub 0/=0.316) at the lower resonance and the two layer design produces a completely planar antenna system which is compatible with microwave and millimeter, MIC, and monolithic MMIC integrated circuits.