This paper presents the investigation on the propagation of microwaves through the square lattice structure constructed by two different materials, glass (εr = 5.5) and poly vinyl chloride (PVC) (εr = 2.38). We report the transmission spectra of these structures that were recorded between 7 and 20 GHz. It is observed that the glass structure of lattice constant 1.4 cm gave a band gap centered around 17 GHz with a gap width of 3.5 CHz and attenuation of 30 dB. With PVC rods, the spectra were recorded for two different lattice constants 1.4 cm and 1.1 cm. The structure of 1.4 cm shows a band gap centered at 16.8 GHz with a gap width of 1.48 GHz where as the structure of 1.1 cm lattice constant shows a band gap centered at 11.17 GHz with a gap width of 2.67 GHz. The attenuation in both cases is around 25 dB. The analysis shows that the gap width is low for structures made of PVC rods when compared to structure made of glass as expected because of the low dielectric constant of PVC. It is also observed that as the filling fraction is increased from 0.14 to 0.23, the gap width increased from 1.48 GHz to 2.67 GHz.