d for a time interval T, we have that the TNDF is given by the time-bandwidth product, i.e., TNDF n 2BT. A more accurate and rigorous analysis is carried out in [67]. Since the time is unlimited, it is possible to arbitrarily increase the value of TNDF by sending waveforms of arbitrarily long duration. In Shannon's theory, this allows to exploit the properties of high-dimensional spaces in terms of energy concentration, transforming "soft spheres" of uncertainty into "hard spheres" of uncertainty [69]. Consequently, the ability to send arbitrarily long waveforms (i.e., arbitrarily long codes) is a key factor in Shannon's theory. The analysis of the degrees of freedom of the electromagnetic field basically shows that the NDF of space-varying waveforms used to encode information is limited by the effective rank of the radiation operator. Consequently, from a mathematical point of view, it is not possible to apply the law of large numbers to transform "soft spheres" of probability to "hard spheres" in "pure" space coding communication. Kolmogorov theory overcomes this problem. When the NDF of the field can be arbitrarily increased, as happens in Massive MIMO [70] wherein arbitrarily electrically large antennas are considered, we can apply the statistical approach used in Shannon's theory considering arbitrarily long data block transmitted in the space domain. Shannon theory in case of bandlimited channels is a well-developed and con- solidated field of research. Consequently, if we are able to obtain a bandlimited approximation of the field in space, we can extend to the space domain the results available in literature regarding communication in the time domain. This is certainly possible. In fact, the set of bandlimited functions with bandwidth W is dense for w 8 in the set of the fields on the receiving domain [21]. Accordingly, it is possible to obtain a representation of the field within any degree of accuracy using bandlimited functions. The sampling representation of the electromagnetic field is routinely used