Window RF Shielding Film Using Printed FSS

Frequency-selective surfaces (FSSs) on thin substrates using screen printing technology are popular due to their flexible nature, low profile, easy installation, and lowcost mass production. This paper proposes the deployment of screen printed FSS on window panes in office buildings and investigates the shielding effect on the radio wave propagation through such structures. The shielding surface is an array of modified meandered squares with a unit cell size 0.083 lambda(o), on a flexible transparent substrate (polyethylene terephthalate) of relative permittivity 3.4. This sheet was then bonded on the window glass. With this FSS, desirable shielding is achieved in the frequency range from 1.5 to 2.5 GHz, with a potential application of shielding for the Universal Mobile Telecommunications System 2 GHz frequency band, while allowing all other bands to pass with little attenuation. Investigations involved the transmission response through the unprinted and printed substrate with and without standard window size float glass. With the optimized FSS design, good agreement was achieved between the theoretical and experimental results, validating the manufactured prototype. Measurements indicate that the FSS window has approximately 38 dB better rejection in 1.5-2.5 GHz band than that of the unshielded window. However, the notch frequency depends on the permittivity and thickness of the glass, and the angle of incidence on the surface. The FSS design can be tuned to shield various frequency bands by rescaling the various physical parameters of the element.