Stop-band frequency-selective structures for controlling back-scattering pattern of L-band linear antenna arrays

This paper presents some numerical and experimental results in respect of reduction of the scattering properties of phased arrays outside their operating range using the band-stop frequency-selective structures (FSS). It reviews the phenomenon of incomplete non-suppression of separate Bragg lobes being caused by the formation of a Fabry-Perot cavity between the FSS and the conductive screen of the phased array. The reviewed approach has been applied to reduce the BSP of the L-band phased array on the basis of the Vivaldi radiator. The matching characteristics have been obtained (SWR <; 2 with in-phase excitation and SWR <; 3, when phased by beam at -45° direction) and the PA directionality. An integrated use of the band-stop FSS and absorbent material has allowed the amplitude of Bragg lobes to be reduced by 5-20 dB within the 8-18 GHz frequency band.