abstract 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 to 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 0.083¿0 × 0.033¿0 × 0.005¿0, where free-space wavelength (¿0) is 1 GHz. © 2016, Springer Science+Business Media New York.
keywords composite right/left handed transmission-lines metamaterial microwave devices planar slotted antennas rf circuits uhf¿shf bands wireless comunications systems cells cytology dielectric materials directional patterns (antenna) efficiency electric inductors helical antennas metamaterial antennas metamaterials microwave antennas microwave circuits microwave devices spiral antennas timing circuits wireless telecommunication systems composite right/left handed transmission lines dielectric substrates free-space wavelengths radiation characteristics rf-circuits slot configuration slotted antennas wireless communication system slot antennas