Multi-band dual-polarized shared aperture microstrip phased array

Multi-band systems are becoming increasingly popular in both military and civil applications such as tactical radar systems and synthetic aperture radar (SAR) systems because their information capacity is significantly higher than single-band counterparts. As the interface between free space and an internal wave guide, a multi-band antenna plays an important role in such systems. A multi-band dual-polarized (MBDP) antenna array can be realized by simply positioning several single-band antenna arrays side-by-side. However, this approach is not desirable because it significantly increases the aperture size and antenna weight. The MBDP shared aperture antenna arrays studied in this thesis can minimize the array size and weight by sharing the aperture of each band. Therefore, it is attractive for some compact systems like space-borne SAR antennas and vehicle based tactical radars. In this thesis, several contributions are made to the knowledge in MBDP shared aperture arrays. They are listed below. 1) Performance improving methods are presented for dual-band dual-polarized shared aperture (DBDP-SA) array. The inter-polarization isolation of the array was improved and the lower-band bandwidth was enhanced for a given antenna thickness. A prototype S/XDBDP-SA microstrip array has been designed and fabricated to verify these methods. Fractional frequency ratio is also achieved in a prototype array by adopting an interleaved dual band embedding structure. 2) A multi-band dual-polarized shared aperture (MBDP-SA) array design method is proposed for SAR applications. To verify the feasibility of this method, an L/S/X tri-band dual-polarized shared aperture (TBDP-SA) array has been designed and fabricated. Good performance has been achieved in all three bands. 3) A novel sandwiched stacked-patch DBDP array is presented, with an aim to enhance the bandwidth in the lower band. Dual band embedding methods are also studied and compared in terms of their bandwidth performance. An L/C DBDP-SA sandwiched stacked patch array has been designed and fabricated to validate this new concept.