Partial-Structure-Oriented Work-Energy Theorem Based Characteristic Mode Theory for Yagi-Uda Array Antennas

Partial-structure-oriented work-energy theorem (WET) governing the work-energy transformation process of Yagi-Uda array antennas is derived. Driving power as the source to sustain a steady work-energy transformation is introduced. Employing WET and driving power, the essential difference between the working mechanisms of scattering objects and Yagi-Uda array antennas is revealed. The difference exposes that the conventional characteristic mode theory (CMT) for scattering objects cannot be directly applied to Yagi-Uda array antennas. Under WET framework, this paper proposes a generalized CMT for Yagi-Uda antennas. By orthogonalizing driving power operator (DPO), the WET-based CMT can construct a set of energy-decoupled characteristic modes (CMs) for an objective Yagi-Uda antenna, and then can provide an effective modal analysis for the Yagi-Uda antenna. In addition, a uniform interpretation for the physical meaning of the characteristic values / modal significances (MSs) of metallic, material, and metal-material composite Yagi-Uda antennas is also obtained by employing the WET-based modal decomposition and the field-current interaction expression of driving power.

Partial-Structure-Oriented Work-Energy Theorem Based Characteristic Mode Theory for Yagi-Uda Array Antennas

Partial-structure-oriented work-energy theorem (WET) governing the work-energy transformation process of Yagi-Uda array antennas is derived. Driving power as the source to sustain a steady work-energy transformation is introduced. Employing WET and driving power, the essential difference between the working mechanisms of scattering objects and Yagi-Uda array antennas is revealed. The difference exposes that the conventional characteristic mode theory (CMT) for scattering objects cannot be directly applied to Yagi-Uda array antennas. Under WET framework, this paper proposes a generalized CMT for Yagi-Uda antennas. By orthogonalizing driving power operator (DPO), the WET-based CMT can construct a set of energy-decoupled characteristic modes (CMs) for an objective Yagi-Uda antenna, and then can provide an effective modal analysis for the Yagi-Uda antenna. In addition, a uniform interpretation for the physical meaning of the characteristic values / modal significances (MSs) of metallic, material, and metal-material composite Yagi-Uda antennas is also obtained by employing the WET-based modal decomposition and the field-current interaction expression of driving power.

Radiation Pattern Reconfigurable Antenna for IoT Devices

Based on the characteristic mode theory, a versatile radiation pattern reconfigurable antenna is proposed. The analysis starts from two parallel metallic plates with the same and different dimensions. By means of two PIN diodes, the size of one of the parallel metallic plates can be modified and consequently the behavior of the radiation pattern can be switched between bidirectional and unidirectional radiation patterns. Moreover, a SPDT switch is used to adjust the frequency and match the input impedance. The reconfigurable antenna prototype has been assembled and tested, and a good agreement between simulated and measured results is obtained at 2.5 GHz band which fits the IoT applications.

Work-Energy Principle Based Characteristic Mode Theory for Wireless Power Transfer Systems

<p>Work-energy principle (WEP) governing wireless power transfer (WPT) process is derived. Driving power as the source to sustain a steady WPT is obtained. Transferring coefficient (TC) used to quantify power transfer efficiency is introduced.</p><p>WEP gives a clear physical picture to WPT process. The physical picture reveals the essential difference between transferring problem and scattering problem. The essential difference exposes the fact that the conventional characteristic mode theory (CMT) for scattering systems cannot be directly applied to transferring systems.</p><p>Under WEP framework, this paper establishes a CMT for transferring systems. By orthogonalizing driving power operator (DPO), the CMT can construct a set of energy-decoupled characteristic modes (CMs) for any pre-selected objective transferring system. It is proved that the obtained CM set contains the optimally transferring mode, which can maximize TC.</p><p>Employing the WEP-based CMT for transferring systems, this paper does the modal analysis for some typical two-coil transferring systems, and introduces the concepts of co-resonance and ci-resonance, and reveals some important differences and connections “between transferring problem and scattering problem”, “between co-resonance phenomenon of transferring systems and external resonance phenomenon of scattering systems”, and “between so-called magnetic resonance and classical electric-magnetic resonance”.</p>

Work-Energy Principle Based Characteristic Mode Theory for Wireless Power Transfer Systems

<p>Work-energy principle (WEP) governing wireless power transfer (WPT) process is derived. Driving power as the source to sustain a steady WPT is obtained. Transferring coefficient (TC) used to quantify power transfer efficiency is introduced.</p><p>WEP gives a clear physical picture to WPT process. The physical picture reveals the essential difference between transferring problem and scattering problem. The essential difference exposes the fact that the conventional characteristic mode theory (CMT) for scattering systems cannot be directly applied to transferring systems.</p><p>Under WEP framework, this paper establishes a CMT for transferring systems. By orthogonalizing driving power operator (DPO), the CMT can construct a set of energy-decoupled characteristic modes (CMs) for any pre-selected objective transferring system. It is proved that the obtained CM set contains the optimally transferring mode, which can maximize TC.</p><p>Employing the WEP-based CMT for transferring systems, this paper does the modal analysis for some typical two-coil transferring systems, and introduces the concepts of co-resonance and ci-resonance, and reveals some important differences and connections “between transferring problem and scattering problem”, “between co-resonance phenomenon of transferring systems and external resonance phenomenon of scattering systems”, and “between so-called magnetic resonance and classical electric-magnetic resonance”.</p>