Wide band dual circularly polarized aperture coupled microstrip patch antenna with bow tie shaped apertures
A wide band aperture coupled microstrip antenna with dual circular polarization operation is proposed. The antenna is designed and simulated to enable the transmission and reception of different circularly polarized wide band signals simultaneously with a single antenna. Instead of conventional rectangular apertures, two orthogonally placed bow-tie shaped apertures fed by a 3 dB branch line coupler are used to obtain wide band performance at S-band using a square radiating patch. A thick, low cost dielectric foam yields further improvement in bandwidth. In simulation, an impedance bandwidth of 28% and axial ratio bandwidth of 15% has been achieved with this geometry. An improvement of 5% in impedance bandwidth and 5.4% in ellipticity bandwidth is obtained over a conventional rectangular aperture. The use of dielectric foam makes the antenna lightweight and low cost. These features make it an ideal element for wide band application as required for personal, mobile satellite and wireless communication systems.