Advanced Superdirective Antennas
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arXiv
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| Format: | Preprint |
| Publié: |
2026
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| _version_ | 1866911421154983936 |
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| author | Krasnok, Alex |
| author_facet | Krasnok, Alex |
| contents | Superdirective (supergain) antennas aim to produce a narrow main beam from radiators that are electrically small compared with the wavelength. Instead of enlarging the physical aperture, they rely on strongly coupled currents, near-field energy storage, and controlled modal interference so that a compact structure radiates with enhanced directivity. This review emphasizes link-relevant evaluation and reporting: realized gain referenced to a stated impedance plane, clearly stated bandwidth definitions (impedance and performance), and robustness to fabrication spread and platform/environmental loading. Two practical implementation routes are surveyed. The first uses resonant, tightly coupled arrays, including fully driven arrays and single-chain designs based on parasitic or reactively loaded elements. The second uses single-body radiators that enforce a targeted mixture of multipoles or resonant/characteristic modes with one or a few feeds, including symmetry-broken dielectric resonators and mixed electric--magnetic designs. Across RF, microwave, and optical regimes, the same penalties recur as superdirectivity is pushed: reduced radiation resistance, rapid impedance variation, narrow usable bandwidth, and strong sensitivity to small perturbations. Beyond geometric synthesis and multi-resonant stacking, the review highlights emerging levers that can shift these trade-offs in specific system contexts: low-loss materials and cryogenic operation to improve efficiency and frequency stability, and time-varying loading and matching (Floquet/parametric approaches) that can relax linear time-invariant bandwidth constraints, at the cost of added control complexity and spectral conversion. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_04121 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Advanced Superdirective Antennas Krasnok, Alex Optics Applied Physics Superdirective (supergain) antennas aim to produce a narrow main beam from radiators that are electrically small compared with the wavelength. Instead of enlarging the physical aperture, they rely on strongly coupled currents, near-field energy storage, and controlled modal interference so that a compact structure radiates with enhanced directivity. This review emphasizes link-relevant evaluation and reporting: realized gain referenced to a stated impedance plane, clearly stated bandwidth definitions (impedance and performance), and robustness to fabrication spread and platform/environmental loading. Two practical implementation routes are surveyed. The first uses resonant, tightly coupled arrays, including fully driven arrays and single-chain designs based on parasitic or reactively loaded elements. The second uses single-body radiators that enforce a targeted mixture of multipoles or resonant/characteristic modes with one or a few feeds, including symmetry-broken dielectric resonators and mixed electric--magnetic designs. Across RF, microwave, and optical regimes, the same penalties recur as superdirectivity is pushed: reduced radiation resistance, rapid impedance variation, narrow usable bandwidth, and strong sensitivity to small perturbations. Beyond geometric synthesis and multi-resonant stacking, the review highlights emerging levers that can shift these trade-offs in specific system contexts: low-loss materials and cryogenic operation to improve efficiency and frequency stability, and time-varying loading and matching (Floquet/parametric approaches) that can relax linear time-invariant bandwidth constraints, at the cost of added control complexity and spectral conversion. |
| title | Advanced Superdirective Antennas |
| topic | Optics Applied Physics |
| url | https://arxiv.org/abs/2602.04121 |