Design of a S/X band Dual-Polarized Microstrip Array Antenna for Radar Application

Office of Naval Research (ONR) of U.S.A navy has been carrying out research about advanced multifunction radio frequency concept (AMRFC) to apply the Multifunction Electronic Warfare & Electronic Support (MFEW ES) system to the future navy battleship [1]. In order to that conventional radar and communication antennas need to be active phased array antennas that can provide multi-functions such as radar, electronic warfare, communication, and navigation [2]. In general, multiband operation is used to implement multi-functions while dual-polarization scheme is adopted to enhance the isolation between Tx and Rx. Many researchers have been trying to find dual-band dual-polarization phased array antenna techniques for satellite, wireless communications and synthetic aperture radar (SAR) applications [3]. In [4], dual-frequency dual-polarized antenna for airborne applications was proposed, but the bandwidth was below 2% at the desired Sand Xband. In [5], L/X dual-band dual-polarized planar array for SAR applications was proposed, but both Land X-band bandwidth was also narrow. Another dual-band dual-polarized antenna for WLAN application was presented in [6]. However, it cannot be utilized for the dual-band dualpolarized (DBDP) radar application due to its complex structure. Although several DBDP antennas have been reported, it is still quite difficult to apply them to practical radar systems due to their narrow bandwidth and complex structure. In this paper, a S/X band dual-polarized microstrip array antenna for an AMRFC radar application was proposed. By using a circular patch with modified L-probe feed for S-band and stacked diamond-shaped patch with parasitic element for X-band, a DBDP array with a frequency ratio of about 1:3 can be proposed.