Electrically small complementary split-ring resonator antenna on eighth-mode substrate integrated waveguide

An electrically small substrate integrated waveguide (SIW) antenna is proposed at 5.22 GHz. Its electrical size is reduced by a complementary split-ring resonator which is loaded on the eighth-mode SIW (EMSIW). The EMSIW occupies only 12.5% of the conventional SIW with the same dominant resonant frequency. The S-parameters and radiation patterns are investigated by full-wave simulation and measurements. Results show the omnidirectional radiation pattern with a 4 dBi peak gain.