Design of dual-band low RCS A-sandwich radome co-designed with low profile antenna for airborne modern radar systems

In this paper, a low-radar-cross-section (RCS) A-sandwich radome is designed using a double-layer frequency-selective surface (FSS) for airborne radar applications. The FSS elements are printed selectively on the top and bottom skin layers of the radome’s dielectric slab. The proposed radome exhibits dual-bandstop responses at the lower and upper sides of the test antenna’s operating frequency, centred at 5 GHz. The radome wall thickness is optimised to about one-quarter wavelength to realise a thin phase-cancellation structure for out-of-band RCS reduction. The overall dimensions of the proposed A-sandwich radome are 120 mm × 120 mm × 16.016 mm. The RCS performance of the radome is tested for different radome-to-antenna heights, and the results are presented. A prototype is fabricated and measured to verify the design concept. The measured results show a −10 dB monostatic RCS reduction bandwidth of 0.68 GHz and 0.67 GHz at 3.69 GHz and 6.7 GHz, respectively. Peak RCS values of −17.31 dB and −15.57 dB have also been observed at these frequencies.