Space-Time Reversal Symmetry Properties of Electromagnetic Green's Tensors for Complex and Bianisotropic Media

Abstract

Abstract-Space-Time reversal symmetry properties of free-Space electromagnetic Green's tensors for complex and bianisotropic homogeneous media are discussed. These properties are defined by symmetry of the medium under consideration, of the point sources and of the vector S connecting the source and the point of observation. The constraints imposed on Green's tensors by the restricted Time reversal, by the center and anticenter of symmetry are independent on the vector S orientation. Other Space-Time reversal operators lead to constraints on Green's tensors only for some special directions in Space. These directions are along the (anti)axes and (anti)planes and normal to the (anti)axes and (anti)planes. The full system of the continuous magnetic point groups for description of Space-Time reversal symmetry of Green's tensors is defined and a general group-theoretical method for calculation of simplified forms of Green's tensors is presented.

Time-Reversal Microwave Imaging Based on Random Configuration of Transmitters or Receivers

“…But a new method, which utilizes UWB operation is time reversal (TR) technique introduced by Fink [1]. The TR technique is based on a fundamental symmetry of physics, i.e., the time reversal invariance [2]. In the TR operation, because of time reversal invariance in lossless media, signals emitted from a source can automatically be refocused on the original source location, when being captured and time reversed by a time reversal array.…”

Subwavelength Array of Planar Triangle Monopoles With Cross Slots Based on Far-Field Time Reversal

“…Curves "Antenna-1", "Antenna-2", "Antenna-3", and "Antenna-4" stand for the nor- Experiment results for the normalized peak values of the received TR signals at the four elements of the subwavelength array constructed with the monopole shown in Figure 1(b). Curves "Antenna-1", "Antenna-2", "Antenna-3", and "Antenna-4" stand for the normalized peak values of signals, A i,1 (i = 1, 2, 3, and 4), A i,2 , A i, 3 , and A i,4 , respectively. characteristics would not have been achieved.…”

“…Antenna system has wide applications in mobile electronics such as wireless mobile communication, radio frequency identification (RFID), and wireless sensor network [1][2][3][4][5][6][7][8][9][10][11][12][13]. These systems, aiming to achieve multiple-antenna design with multiple independent channels on sizelimited platforms, always seek means to greatly improve the capacity and data-rate of communication.…”

“…Featuring of its adaptive focusing characteristic, TR technique has been used in lots of applications such as underwater acoustics communication, medical, electromagnetic imaging, and ultra-wideband wireless communication [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Recently, one completely new approach to achieve super-resolution has been offered by TR technique [20][21][22].…”

Multiple Antenna Transmission Technique for Uwb System

“…In this case, the scheme using the multiple transmit and receive antennas for spectrally efficient transmission is alternative solution [7], and moreover multi-input multi-output (MIMO) systems provide significant capacity gain in proportion to the number of antennas [8][9][10][11]. Therefore, we apply MIMO architectures using space-time block code (STBC) [13,14] to MB-OFDM UWB system. In the wireless communication environment, the channel modeling and channel estimation are important [15,16].…”