The characteristic mode theory (CMT) can provide physically intuitive guidance for the analysis and design of antenna structures. In CMT applications, the antenna current distribution is decomposed into the superposition of multiple characteristic modes, and the proportion of each current mode is characterized by the modal weighting coefficient (MWC). However, different characteristic currents themselves have different radiation efficiencies reflected by the eigenvalues. Therefore, from the perspective of the contribution to the radiation field, the modal proportion should be more accurately determined by the combination of the modal weighting coefficient and the mode current itself. Since the discrete mode currents calculated using the electromagnetic numerical method are distributed on the whole conductor surface, we can actually use the radiation field to quantify the modal proportion or estimate it using the far field in the maximum radiation direction. The numerical examples provided in the paper demonstrate that this modal proportion can effectively evaluate antenna performance.

Nanofiltration (NF) with adsorptive membrane technologies are one of the most promising methods for the efficient treatment of industrial wastewater having toxic heavy metal ions. The present investigation deals with the fabrication of nanocomposite Fe3O4@MXene membranes by self‐assembly of Fe3O4 nanoparticles (NPs) and two‐dimensional (2D) MXene nanosheets on the surface of cellulose acetate (CA) base membrane. The Fe3O4 NPs were found to be uniformly dispersed on the MXene sheet structure and thus expanded the 2D nanochannel of MXene. The water flux and the removal ratio of heavy metal ions by this nanocomposite membrane were found to improve significantly, compared to the virgin MXene membrane. Under the synergistic effect of layer sieving and the adsorption ability, the composite NF membrane was found to achieve a maximum of 63.2% for Cu2+, 64.1% for Cd2+ and 70.2% for Cr6+ removal from wastewater, respectively. Moreover, Fe3O4@MXene membrane also exhibited good recycling ability after washing by HCl solution.

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