Enhancing the Number of Modes in Metasurfaced Reverberation Chambers for Field Uniformity Improvement

Abstract

The use of metasurfaces to increase the number of modes, lower the operating frequency, and improve the field uniformity in reverberation chambers (RCs) is investigated in this paper. The method used to improve the field uniformity and decrease the resonance frequencies is based on increasing the number of modes by using the concept of subwavelength cavities. The resonance frequencies of a RC with metasurface wall are derived and expressed analytically in terms of macroscopic characteristics. Simulation of the reflection phase of the unit cell is then given as a guideline to choose the required microscopic parameters of the designed metasurface. The mode density in such subwavelength RCs is then obtained using a numerical eigenmode solver. Compared to traditional RCs, a much higher modal density is obtained at low frequencies. The standard deviation of the field uniformity in the test volume of the RC corresponding to different types of metasurface walls is finally compared. It is shown that by increasing the number of modes in the RC at the lower band, the operating frequency decreases and the field uniformity of the RC is improved.

Design, analysis, and validation of Radio Research Agency reverberation chamber

“…It can be noted that the selected number of experimental frequency points are much higher than the defined minimum limits of Table 1. It was done as the higher number of frequency/stirrer samples are recommended for the more accurate estimation of the field uniformity at low frequencies 8,18,25 . Figure 13 shows the actual picture of the experimental settings inside the RRA RC.…”

“…It was done as the higher number of frequency/stirrer samples are recommended for the more accurate estimation of the field uniformity at low frequencies. 8,18,25 Figure 13 shows the actual picture of the experimental settings inside the RRA RC.…”

Characterization of Reverberation Chamber - A Comprehensive Review

“…The procedure is applicable even for the case when more than one antennas are present in an RC. In (20), η o is the wave impedance, represents the permittivity of the RC propagation medium, and η depicts the efficiency of the antenna which can be estimated using (19). The term 1 − | S 11 | 2 in (20) also represents antenna efficiency (see 19).…”

“…In (20), η o is the wave impedance, represents the permittivity of the RC propagation medium, and η depicts the efficiency of the antenna which can be estimated using (19). The term 1 − | S 11 | 2 in (20) also represents antenna efficiency (see 19). This simplifies (20) to (21).…”

Parametric Testing of Metasurface Stirrers for Metasurfaced Reverberation Chambers

“…The main conclusion in [ 11 ] was that although the field uniformity was only somewhat improved for the MRC with the rotating 1-bit coding diffusion metasurface (as compared to the traditional one), an extended MRC test zone was achieved due to the lack of mechanical stirrer. In [ 13 ], we analyzed the physical mechanism for increasing the number of modes, lowering the operating frequency, and improving the field uniformity in the reverberation chambers, and concluded that a designed sequential metasurface provided better stirring effect than the random one. After dealing with these studies, it is concluded that the coding metasurface stirrer can improve the uniformity of field distribution in the MRC, and can replace the traditional metallic stirrer.…”