A Triangular Patch Antenna with Bow Tie Aperture Coupling for Improved Ellipticity Bandwidth

Improvement in ellipticity bandwidth with an equilateral triangular shaped microstrip patch antenna is analyzed in this paper. The triangular patch is electromagnetically coupled using two orthogonally oriented bow tie shaped apertures fed by a 3dB 90deg hybrid for dual polarization operation. The radiating triangular patch has an optimized side length of 52.0 mm. The antenna is designed to transmit and receive the two differently circularly polarized wide band signals simultaneously with a single antenna. The use of a thick, low cost dielectric foam yields further improvement in bandwidth. A 2:1 impedance bandwidth of 38% and 3 dB axial ratio bandwidth of 23% has been achieved practically with the optimized geometry. An improvement of 7.16% in impedance bandwidth and 10.14% in ellipticity bandwidth is obtained over a patch of similar geometry with conventional rectangular shaped apertures. The use of dielectric foam makes the antenna light weight and low cost. The above features make it an ideal element for wide band application as required for Personal, Mobile Satellite and Wireless Communication Systems.