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This article proposes a novel compact wideband dielectric resonator antenna design that incorporates inhomogeneous material distribution in a cubic structure. Specifically, in this design, the cubic dielectric resonator antenna is divided into multiple small blocks, and a continuous genetic algorithm is employed to optimize the material property of each block in order to maximize the radiation bandwidth. As a result, a cubic dielectric resonator antenna with inhomogeneous material distributions is designed and tested. In measurement, the proposed compact dielectric resonator antenna design exhibits 64.9% impedance bandwidth (4.08–8 GHz), considerably higher than the bandwidth of the initial homogeneous dielectric resonator antenna. The maximum system gain achieved over the frequency range is 9 dB at 7 GHz, with a peak measured system efficiency of 90.6%. 

Improving the photon-magnon coupling strength can be done by tuning the structure of microwave resonators to better interact with the magnon counterpart. Planar resonators accommodating unconventional photon modes beyond the half- and quarter-wavelength designs have been explored due to their optimized mode profiles and potentials for on-chip integration. Here, we designed and fabricated an actively controlled ring resonator supporting the spoof localized surface plasmons (LSPs), and implemented it in the investigation of photon-magnon coupling for hybrid magnonic applications. We demonstrated gain-assisted photon-magnon coupling with the YIG magnon mode under several different sample geometries. The achieved coupling amplification largely benefits from the high quality factor (Q-factor) due to the additional gain provided by a semiconductor amplifier, which effectively increases the Q-factor from a nearly null state (passive resonance) to more than 1000 for a quadrupole LSP mode. Our results suggest an additional control knob for manipulating photon-magnon coupled systems exploiting external controls of gain and loss.