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In this communication, we present a new method of encoding /decoding information contained in a wave packet using multipath effect. A signal is mixed with an auxiliary signal and sent into an enclosed cavity. The strongly distorted signal transmitted through the cavity is then sent to a receiver, where it is time reversed and sent to a second enclosed metallic cavity that is strictly identical to the first one. As a result, the waveform of the initial signal is reconstructed at a point of the second cavity that is equivalent to the point of the first cavity due to the spatial and temporal focusing. Using the mechanism, secure wireless data transmission is carried out. Finally, the impact of the size of the cavity on intersymbol interference and the frequency dispersion caused by frequency selective fading are discussed. Such a communication system ensures a high level of security. [ABSTRACT FROM AUTHOR]

A novel time-reversal subwavelength transmission technique, based on pulse-shaping circuits (PSCs), is proposed. This technique removes the need for complex or electrically large electromagnetic structures by generating channel diversity via pulse shaping instead of angular spectrum transformation. It is shown that, compared to our previous time-reversal system based on chirped delay lines, the PSC approach offers greater flexibility and larger possible numbers of channels, i.e., ultimately higher transmission throughput. The superiority of the PSC time-reversal system is also demonstrated experimentally. [ABSTRACT FROM PUBLISHER]

In this communication, a new approach for sub-wavelength array design based on time reversal technique is proposed. Three chirped delay line with different group delay slopes are embedded into a sub-wavelength array as independent feeding lines. With the pre-distortions provided by the chirped delay line, when time reversal technique is used, the novel sub-wavelength array has far-field super-resolution focusing property. Different from evanescent-to-propagating spectrum conversion mechanism, the new approach can improve the radiation efficiency of the sub-wavelength array because no micro-scatterers in the near field of the array elements are required. [ABSTRACT FROM PUBLISHER]

With the aid of specific microstructures in a subwavelength array, time-reversed electromagnetic wave can display spatial super-resolution focusing in far-field zone. A subwavelength array of planar monopoles is proposed in this paper. Each element of the array, the planar monopole, is etched aperiodically with many microstructured complementary split rings. An important property of this antenna is that if multiple such planar monopoles are placed face to face, the proposed array can perform time-reversal far-field focusing with a spatial super-resolution as small as one twentieth of a wavelength. The validity of the proposed array with super-resolution characteristics is verified by the communication experiments with a data rate of 660 Mbit/s. The proposed subwavelength array is easy-to-design and convenient for integration. [ABSTRACT FROM AUTHOR]