New CRLH-Based Planar Slotted Antennas with Helical Inductors for Wireless Communication Systems, RF-Circuits and Microwave Devices at UHF-SHF Bands

Two novel planar slotted-antennas (PSAs) are presented that exhibit good radiation characteristics at the UHF-SHF bands. The proposed antennas are constructed using metamaterial unit-cells constituted from capacitive slots etched in the radiating patch and grounded spiral shaped inductive stubs. The proposed PSA design is fabricated on a commercially available dielectric substrate, i.e. Rogers RO4003 with permittivity of 3.38 and thickness of 1.6 mm. The first PSA comprising five symmetrical unit-cells of slot-inductor-slot configuration operates over a wide bandwidth extending from 1–4.2 GHz with a peak gain of 1.5 dBi and efficiency of 35% at 2 GHz. The second PSA consists of ten asymmetrical unit-cells of slot-inductor configuration on the same size of substrate as the first PSA, enhances the antenna gain by 2 dB and efficiency by 25% and operates over 0.75–4.5 GHz. The asymmetrical unit-cell effectively increases the aperture size of the antenna without comprising its size. The electrical size of the antenna is 0.083λ0×0.033λ0×0.005λ0, where freespace wavelength (λ0) is 1 GHz.