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This work presents and investigates a novel high-performance antenna design for remote sensing and satellite communications applications that is compact and lightweight. The performance requirements include dual-polarization, wide impedance bandwidth, low cross-polarization, high gain, and high aperture efficiency. To simultaneously achieve all these qualities is challenging and a combination of compatible performance enhancement techniques was selected and derived. A new antenna design, namely an octagonal cavity-backed radiating open prism (OCROP) antenna, was first introduced. The antenna is orthogonally and differentially fed to provide dual-polarization and low cross-polarization. The impedance bandwidth is increased by combining the resonances from the radiating feedlines and the open prism. The corner truncated octagonal ground cavity, instead of a more commonly seen square ground plane or square ground cavity, is used to further suppress the cross-polarization and enhance the gain and aperture efficiency. To show the superiority of the octagonal design, it was compared with a square ground cavity backed antenna. To further improve the gain of this novel antenna, its array and flared configurations are considered, investigated, and compared. The array design offers higher gain and aperture efficiency, while the flared design can provide lower cross-polarization. To achieve higher gain with the flared design, a larger flare angle was chosen which increased cross-polarization. To remedy the problem of the increased cross-polarization, a new iris design concept is proposed and investigated. It shows that this method can successfully suppress the cross-polarization of the flared design. This concept is general and has the potential to be applied to other types of aperture antennas. The design concepts and the simulation results are verified by fabricating and testing two prototypes, i.e., with and without a flare.

This work reports experimental investigation and numerical validation of millimeter-sized Spherical Bragg Resonators (SBRs) fabricated using 3D printing technology. The frequency dependencies of the reflection and transmission coefficients were analyzed, and eigenfrequency values were calculated to examine the density of photonic states in air/PLA-polylactide SBRs, showing the appearance of an eigenmode and an increase in the local density of states in the core of a defect cavity. A decay rate enhancement of ∼10² was obtained for a dipole placed in the core of the defect SBR. The study also investigated the influence of the source position on the resonator's electromagnetic wave energy. Scattering efficiencies up to order twelve of the multipole electric and magnetic contribution in a 10-layer SBR were calculated to validate the presence of the resonant modes observed in the scattering measurements performed for parallel and perpendicular polarizations. The results demonstrate that SBRs can act as omnidirectional cavities to enhance or inhibit spontaneous emission processes by modifying the density of electromagnetic states compared to free space. This finding highlights the potential of SBRs engineering spontaneous electromagnetic emission processes in various applications, including dielectric nanoantennas, optoelectronics devices, and quantum information across the entire electromagnetic spectrum.

RÉSUMÉ: The design and implementation of a dual wide-band mushroom-shaped antenna are presented in this paper. The antenna consists of a cylindrical dielectric resonator (cDRA), a cylindrical dielectric rod as a waveguide (cDR), and a dielectric lens (DL). The cDRA in conjunction with the DL acts as a sub-6-GHz antenna. At the mm-wave band, the small cDR acts as a waveguide, which transfers the wave from the feed toward the larger cDRA and the DL in order to produce a high gain. A dual wide-band antenna is designed and fabricated with different dielectric constants for the cDRA/cDR and the DL. 3D printing is utilized to precisely control the dielectric constant of printed component. Measurement results show a maximum gain of 6.4 dB at 5.3 GHz with a 21% 3-dB gain bandwidth and 12.7 dB at 31.5 GHz with a 26.2% 3-dB gain bandwidth. The sub-6-GHz band exhibits a measured 10-dB return loss bandwidth of 21% (centered at 5.15 GHz), and the mm-wave frequency band demonstrates a measured 10-dB return loss bandwidth of 26.2% (centered at 30.5 GHz).