Transmission of convoluted periodic loop element with selective reflection

The transmission and reflectivity of electromagnetic energy across a planar layer consisting of periodic arrays of convoluted loop elements (with interelement spacing of 6.08 cm ) is investigated in the lower microwave spectrum at 1.575 GHz ( λ = 19 cm ) . This relatively close spacing is achieved by convoluting the conventional 1 λ square loop element at its four corners. The close interelement spacing provides a stable passband frequency response over wide angles of wave incidence, while the convoluted segment provides a short circuit response when the segment length is λ ∕ 4 long. The short circuit will provide a reflection to the electromagnetic energy at the selected band-stop frequency range. Various design considerations have been adopted to meet the challenge of ensuring a common passband bandwidth of 22.47% ( 1.5 - 1.95 GHz ) , with a transmission loss of less than 0.5 dB for scan angles up to 45° in both TE and TM polarization.