Comparative Study of Low Sidelobe Time Modulated Linear Arrays with Different Time Schemes

Abstract

Low sidelobe antenna arrays usually require tapered excitations with very high dynamic-range ratios, which is often one of the difficulties encountered in practical implementation. By introducing an additional degree of freedom – time – in the design, time modulated antenna arrays have very low excitation dynamic-range ratios, even in the case of uniform excitations. In this paper, the feasibility of using different types of time modulation schemes to design low sidelobe time modulated linear arrays is discussed. The time modulation schemes examined in this study include variable aperture sizes (VAS), unidirectional phase center motion (UPCM), and bidirectional phase center motion (BPCM). It is shown that all three types of time modulation schemes can be used to synthesize a specific low sidelobe patterns, despite different array characteristics such as sideband levels and reduction in gain. Experimental results of a prototype 16-element printed dipole linear array confirmed the theoretical results.