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| Design | Characteristic features |
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| (1) | PV cells as a metamaterial layer, dual band (lower band: 70 MHz bandwidth around 1185 MHz, upper band: 3400–3600 MHz), high gain (17.3 and 6.6 dBi at 3.5 and 1.23 GHz, resp.) [70] |
| (2) | Omega and reversed-omega elements in the unit cell, improved transmission between 13 and 17 GHz [72] |
| (3) | DPS and DNG media, gain increase to 6 dBi, beamwidth reduction by 37.5% [73] |
| (4) | Highly transparent at normal incidence, reduced reflection at oblique incidence, no phase change upon transmission [74] |
| (5) | Gain enhancement through 9 subwavelength holes by about 3.4 dB [75] |
| (6) | A 4-dB improvement in radiation pattern for blind spot angle, wide-angle impedance matching, blind spot mitigation [3] |
| (7) | DPS and DNG layers, gain increase by 3.45 dB, increase in the directivity by 2.9 dB, bandwidth improvement [78] |
| (8) | Refractive index smaller than unity, CP antenna, 3-dB improvement of the gain, increase of the bandwidth [79] |
| (9) | Heat-resistant structure, stable transmission at different incident angles, bandwidth increase from 10 GHz to 12 GHz by changing the size of unit cells [80] |
| (10) | Uniaxial medium with large permittivity along the anisotropy axis, operation on the near field, TM polarization transparent, broader radiation pattern, nearly eliminated interference within the cavity [81] |
| (11) | Polarization- and frequency-selective metasheets in X and Ka bands [82] |
| (12) | Disc-shaped electrically large metasheet, a hybrid approach (PO/FEM) to calculation of transmission [8] |
| (13) | Control of the phase of the transmitted wave by DC voltage, scanning over a wider range of radiation angle (up to 60° steering angle), 8 dBi maximum gain, beamwidth less than 7° [83] |
| (14) | Nonreciprocal ferrite structure, improved isolation, 21-dB difference between S12 and S21 at 8 GHz, transmission along one direction and attenuation along the opposite direction [85] |
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