S band dual polarized antenna for DAB application

This paper presents a dual polarized antenna system incorporating a low profile annular ring patch antenna fed by short circuit pins incorporating 90/spl deg/ phase delay element for circular polarization (CP) and a reactive-loaded monopole linear polarized (LP) antenna which is connected to the circular patch and two additional wires. The simulated return loss characteristics of the proposed antennas reveal bandwidth greater than 100 MHz for VSWR < 1.5 criterion which is much wider than the required bandwidth (25 MHz) at desired center frequency. The calculated axial ratio is less than 3 dB in the entire frequency region. Even further, the proposed CP antenna provides good broadside radiation patterns, while LP antenna radiation pattern is very similar to those of the monopole antennas. The gain of the CP and LP antennas are calculated to have maximum +4.6 dBi and minimum -1.5 dBi, respectively.