Table 2.
Summary of various reconfigurable/tunable antennas at sub-6-GHz bands.
| Reference | Operating frequency band (GHz) | Antenna element type | Material used | Beam-steering/ Reconfigurability method | Array geometry | Antenna gain (dBi) | Smart reconfigure feature |
|---|---|---|---|---|---|---|---|
| [82] | 4.9 to 5.9 | Microstrip | F4B TM-2 | SP4T and phase shifter | Linear and planar, 1 × 4, 2 × 4, and 4 × 4 | 11.16 to 17.25 | Selectable sectoral coverage from 90° to 360° |
| [52] | 1.35 to 2.19 | Microstrip | Multilayer, RO 4350, and FR4 | Varactor diode | Planar, 4 × 4 | 11.85 to 15.28 | Polarization agility and frequency reconfigurability |
| [32] | 9.6 to 10.2 | Microstrip | Multilayer, RO 4350B | PIN diode | Linear, 1 × 32 | 17.8 | Beam-scanning from −60° to 60° |
| [86] | 5.1 to 5.9 | Microstrip | Multilayer, R05870, and RO5880 | PIN diode | Circular configuration | 10 | 360° beam-steering |
| [51] | 1.5 to 2.4 | Microstrip | Rogers 5880 | Varactor diode | Circular, 4 elements | 13.29 | Frequency agility and polarization reconfigurability |
| [172] | 1.97 to 2.54 | Microstrip | FR4 | Varactor | Triangular | 3.1 | Frequency, polarization and pattern reconfiguration |
| [173] | 4.63 to 5.07 | Microstrip | Multilayer, RO4350, RO4450, TLY-5 | Pin diodes and RF switch | Planar array | 7.5 to 10.5 | Beam switching and polarization reconfiguration |
| [174] | 2.4 to 2.48 | Microstrip | RO 5880 | Butler matrix | Linear 1 × 4 | 11.04 | Beamforming using Butler matrix |
| [175] | 0.9 to 1.5 | Microstrip | Multilayer, RO4003C, 4450B | RF MEMS switch | Single element | 4.5 to 6.5 | Frequency agility and 4-state polarization diversity |
| [176] | 1 to 3 | Microstrip | Rogers 5880 | PIN diode | Circular configuration | −3 to 3.2 | Frequency and polarization reconfigurable |
| [81] | 2.4 | Microstrip | FR4 | PIN diode | Single element | 5.18 to 5.32 | Beam-steering in 4 directions |
| [177] | 2.4 | Microstrip | FR4 | PIN diode | Circular configuration | 4.5 | Pattern reconfigurability |
| [178] | 1.8 to 2.2, 2.85 to 3.15 | Monopoles and parasitic elements | - | PIN diode | Circular configuration | 5.5 | 360° beam-steering and adaptive beamforming |
| [179] | 2.3 to 2.55 | Folded monopoles with parasitic elements | FR4 | Varactor | Circular configuration | 4 | Beamforming and 360° beam-steering in azimuth |
| [180] | 2.4 to 2.5 | Microstrip | RO 4003C | PIN diode | Single element | 6.5 | Beam-steering |
| [181] | 2.4 | Microstrip | Taconic (TLY-5) | PIN diode | Circular configuration | 7.01 to 8.01 | Multidirectional pattern reconfiguration |
| [182] | 3.44 to 3.6 | Microstrip | - | PIN diode | Circular configuration | 8 | Pattern reconfiguration |
| [183] | 5 to 5.2 | Yagi-Uda dipole | R0 6010 | PIN diode | Planar | 7.5 to 10 | Beam switching and pattern reconfiguration |
| [88] | 2.36 to 2.6 | Metamaterial | RO 4003C | Varactor | Planar | 5.77 to 6.05 | Pattern reconfigurability |
| [90] | 10 GHz | Metamaterial | Multilayer, RO 4003C | Varactor | Planar | 5 to 10 | Beam-steering |