Photon Tunneling In A Theoretical Study, Abnormal Propagation Of Electromagnetic Waves In Free Space

It is a cross-issue involving many subjects simultaneously for us to study the photonic tunneling effect or the anomalous propagation of electromagnetic wave, and, as a young and spunky field, it has theoretical and practical interest. However, as for this field, its development in theory is behind that in experiment and is far from maturity. In this field, some experimental results, which contradict our traditional theories, have not been obtained a satisfactory interpretation theoretically. What is more, to our surprise, this anomalous propagation of electromagnetic wave can also take place in free space. In this paper, our main aim lies in trying to provide a reasonable interpretation theoretically to this phenomenon.We discuss and analyze the existing experiments and theories related to the anomalous propagation of electromagnetic wave, from which we summarize the laws corresponding to this experimental results, and point out that there exist some problems and errors in those theories. On the basis of which, we provide a new interpretation for the anomalous propagation of electromagnetic wave in free space. Furthermore, we give a united interpretation for all kinds of anomalous propagation phenomena of electromagnetic wave, as well as some new theoretical deductions. More specifically, we draw some conclusions as follows: 1) as for the anomalous propagation phenomena of electromagnetic wave in free space, its existing interpretations are problematic and erroneous, for example, in these interpretations, some mathematical quantities without any physical meaning are introduced artificially, and the group velocity is confused with the apparent phase velocity; 2) with respect to the anomalous propagation phenomena of electromagnetic wave in free space, it is governed by the laws of the near-field of antenna, and some of them are possible related to the electromagnetic wave being described by the Bessel function with imaginaryargument; 3) there exists an intrinsic relation between the near-field and the evanescent field, the latter is a particular representation of the former. Correspondingly, all kinds of anomalous propagation phenomena of electromagnetic wave have the same physical origin, i.e. the virtual photon process, then these phenomena have a mature reason in quantum field theory, and do not contradict the law of causation; 4) the Maxwell equations with sources may have the superluminal solutions satisfying the principle of causality.In view of the fact that, studying the issue mentioned in this paper, is beneficial to our farther researching and holding for the physical laws of the near-field or evanescent field, this issue not only can promote the innovation of the traditional theories and deepen the understanding to our world, but also has practical value in engineering and technology. For example, the achievements in research of the near-field or evanescent field can be applied in the terahertz technique that rising at present, and can apply in the technique of near-field scanning optical microscopy, of the optics and biology sensor, of near-field nano-optics, of the evanescent field spectroscope, etc.