A Miniaturized Frequency Selective Dual Band Metamaterial Absorber for Mutual Coupling Reduction between MicrostripAntennas

This paper proposes a dual-band metamaterial-inspired microwave absorber using a periodic geometry of metal backed frequency selective surface (FSS). The architecture of the FSS unit cell consists of a square ring and a Jerusalem cross, which is printed on a grounded FR-4 substrate. The square unit cell of the FSS has a periodicity of 8.6 mm or 0.072 λ
L
, where λ
L
is the wavelength at the lower resonant frequency. The dual-band FSS resonates at 2.5 and 5.17 GHz with absorbtivities of > 96 %. The absorption property of the structure is achieved to be polarization insensitive and high oblique angle stable of > 40°. The 1D array of the absorber unit cells is placed between two microstrip antennas to reduce the surface wave coupling. The absorber-loaded multiple input multiple output (MIMO) array exhibits an isolation improvement of > 20.2 dB and an enhanced return loss bandwidth (BW) of 7.1 % with center at 2.52 GHz.