Enabling Wide Bandwidth in Substrate-Integrated Waveguide Slot Antennas by Using Low-Index Metamaterials

This paper presents a solution to overcome the inherently limited bandwidth of substrate-integrated waveguide (SIW) slot antennas. It is analytically shown that by decreasing the permittivity of a dielectric loaded slot antenna, the resulting bandwidth increases significantly, where the widest bandwidth can be achieved when the permittivity of the dielectric is less than unity. To demonstrate this concept, a rectangular SIW slot is loaded by an array of thin wires to realize the desired low-index metamaterials (MTMs), which consequently results in a single-layer, compact, and cost-effective structure. We have measured an impedance bandwidth (|S11|