This work proposes the combined use of split ring resonators (SRR) in a middle slab position with side slab ones to create two different passbands (stopbands) below (above) the cutoff frequency in a rectangular waveguide. The same effect can be achieved by using only SRR loadings on the side walls with different sizes of the elements on each side. Furthermore, by combining both techniques, three bands can be obtained. By adjusting the SRR sizes and with the dielectric materials, the passbands (stopbands) can be targeted at the desired frequencies. Both types of multiband structures could find application in multifunction array antennas comprising interlaced arrays of open-ended waveguides. The work is supported by experimental results.