Closely Spaced Tri Resonance Wide Band FSS for S/Ku/Ka Band

This paper reports a frequency selective surface with three closely spaced resonances in reflection band. The unit cell element for the designed frequency selective surface (FSS) has two layers of circular loop patches on dielectric, stacked with foam. The reflection band for developed FSS is Ka band and transmission bands are S and Ku bands. Analysis results show that transmission for all three resonances is in range -35 dB to -45 dB in reflection band and in S band it is ≤ -0.15 dB, for Ku band it is ≤ -0.25 dB. Very close resonances with second to first resonance ratio 1.2 and third to second resonance ratio 1.36, have been achieved. Also the reflection to transmission band ratio is 1.3, which is very less. The developed FSS shows good polarization and angle of incidence stability up to 40°. The developed FSS found to have a wide bandwidth for 10 dB reference with 61.8% fractional bandwidth. The measured transmission coefficient is in good matching with analysis results.