Semiconductor deposition on magnetron's cathode surface using different materials such as gallium nitride (GaN) and silicon carbide (SiC) semiconductors is conducted to grow approximately 80, 100 and 120 nm plasma layers. The cathode is then used to generate high frequency and low-power microwave for further comparison and analysis with the conventional magnetron operation. Parameter of analysis to identify the efficiency includes electron drift velocity, harmonic order, total harmonic distortion, low harmonic distortion, and spectrum observation. The sputtered cathode of the magnetron is used to generate a low-power microwave observing a generator efficiency up to 93 and 88% for GaN and SiC materials, respectively, compared to the conventional material, which observes 37% of efficiency at 2450 MHz, 5 W. Also reported is the quality of semiconductor sputtering on the magnetron cathode, which was manipulated by the deposition period, temperature, and plasma layer growth thickness.

This work describes the design of a rectenna array exploiting orthogonal, closely-spaced UHF monopoles for orientation-independent RF energy harvesting to energize a passive tag, designed for UWB localization, with wake-up radio (WUR) capabilities. To reach this goal, different RF networks are studied to simultaneously realize RF decoupling of the antenna elements and matching of the radiating elements to the non-linear network of rectifiers. The design is performed for a wide power range of the RF incoming signals that need to be exploited for both energizing the passive tag and for providing energy autonomy to a WUR sub-system, used to minimize the long-term power consumption during tag standby operations. Two meandered cross-polarized monopoles, located in close proximity, and thus highly coupled, are adopted for orientation-insensitive operations. The combining RF network is reactive and includes an unbalanced power divider to draw a fraction of the harvested energy to a secondary way for WUR operations. The performance of the harvester is first optimized by EM/non-linear co-design of the whole system over an interval of low RF power levels. The system has been realized and experimentally validated: the superior results obtained, in terms of both dc voltage and power, with respect to a standard single-monopole rectenna, justify the deployment of the presented tag for the energy autonomy of future generation radio-frequency identification tags for indoor localization.

This paper presents a broadband hybrid slot-dielectric resonator antenna for radiofrequency (RF) energy-harvesting application. The antenna geometry consists of a simple pentagon-shaped dielectric resonator antenna (PDRA) excited by a microstrip feed underlying rectangular slot with narrow notch. It is investigated that the bandwidth of the proposed PDRA is improved significantly owing to electromagnetic coupling between feeding slot and the dielectric resonator. The measured results demonstrate that the proposed PDRA achieves an impedance bandwidth of 110.8%, covering the frequency range from 0.86 to 3 GHz in addition of stable radiation pattern with peak gain of 6.8 dBi and more than 90% radiation efficiency throughout the band, showing its suitability for RF energy harvesting application. For this to be feasible, the developed antenna is matched with the rectifier at two public telecommunication bands of GSM-900 and GSM-1800 using a compact dual-band hybrid matching network. The measured result demonstrates that the proposed dual-band rectenna system provides the peak efficiency of 63 and 59% for a load impedance of 4.7 kΩ at 0.9 and 1.8 GHz, respectively.

Magnetic coupling resonance wireless power transfer technology has attracted worldwide attention in recent years due to its mid-range, non-radiative, and high-efficiency power transfer. However, in regard to its practical applications, there are still some issues that need to be considered and studied with respect to coil design, such as coil structure, and parasitic parameter extraction. This paper investigated the characteristics of magnetic coupling resonance wireless power transfer systems with different coil structures, including circular coils and rectangular coils arranged in parallel. We calculated the magnetic field distributions and mutual inductances by subdividing the receiving coils and computing the magnetic flux density of each subdivision. The proposed analysis was validated by means of the finite element analysis and the experimental results. We investigated the effects of the coil's structure, and topological structures, on the power transfer efficiency. The results demonstrate that using circular coils in parallel is more advantageous than using rectangular coils.