IEEE Transactions on Antennas and Propagation

M. Mishra, K. Dutta, R. S. Kshetrimayum, M. S. Sharawi, A. A. Kishk, S. Chaudhuri and S. Bhunia, "Mutual Coupling Reduction Between Two Tightly Packed Half-Split Cylindrical Dielectric Resonator Antennas”," IEEE Transactions on Antennas and Propagation (Impact factor: 5.7), vol. 71, no. 12, pp. 9974 - 9979, Dec. 2023. {Download paper at IEEE Xplore}

Abstract: An efficient and advanced decoupling technique is presented to significantly reduce the mutual coupling in the E -plane between two tightly-spaced half-split cylindrical dielectric resonator antennas (CDRAs). The proposed design offers around 59% reduction in the overall electrical footprint compared to the reference 2-port full CDRA antenna exhibiting the same mutual coupling performance. This is possible by the vertical placement of copper-cladded FR-4 substrate with air gaps between two halves and maintains the boundary condition to support the dominant HEM 11δ mode of CDRA. A significant reduction in mutual coupling is obtained precisely at the antenna resonance by controlling the dimensions of the decoupling structure, leading to its minimum value. The proposed technique appears flexible and provides a comprehensive design guideline to tune the return loss and mutual coupling minima. A detailed analysis is performed with an equivalent circuit model to explain the decoupling mechanism and its precise control for optimal performance. Measured S-parameters show a -10 dB impedance matching bandwidth of 16% (4.54 to 5.34 GHz) and -44 dB mutual coupling at 4.9 GHz, reaching -62.3 dB at 4.86 GHz. Within the operating bandwidth, the measured gain lies between 4.6 and 6 dBi, and the envelope correlation coefficient is below 0.053. The results indicate that the two-port antenna is a good candidate for MIMO communication.

R. S. Kshetrimayum, "Comment on “Compact UWB Monopole Antenna for Automotive Communications”," IEEE Transactions on Antennas and Propagation, vol. 70, no. 2, pp. 1591-1591, Feb. 2022.

Abstract: The equation for diversity gain (DG) for multiple-input multiple-output (MIMO) antenna in the paper authored by M. G. N. Alsath and M. Kanagasabai is incorrect. The correct equation for diversity gain by employing MIMO antennas is provided in this paper. The degradation factor (DF) in the diversity gain due to envelope correlation coefficient (ECC) is also mentioned in this comment paper.

R. S. Kshetrimayum and L. Zhu, "Guided-wave Characteristics of Waveguide Based Periodic Structures Loaded with Various FSS Strip Layers", IEEE Transactions on Antennas and Propagation, Vol. 53, No. 1, pp. 120-124, Jan. 2005.

Abstract: In this paper, frequency-dependent guided-wave characteristics of waveguide based periodic structures loaded with transversal strip layers of frequency selective surfaces (FSS) are extensively studied in terms of per-unit-length transmission parameters, i.e., complex propagation constant and complex wave impedance. Such a periodic structure with various FSS strip layers are in theory characterized using the hybrid method of moments (MoM)-immittance approach so as to derive these two per-unit-length parameters over a wide frequency range. At first, the extracted phase constant of a simple periodic waveguide, loaded with rectangular patch layer, is compared with the available analytical results, thus validating the approach utilized here. Next, the three novel periodic waveguides, loaded with plus, square loop and Jerusalem cross FSS strip layers, are investigated. It is observed that there is slow-wave behavior in the lower passband for the first two whereas the third one exhibits both fast-wave and slow-wave propagation behaviors in the lower passband. Besides, the third one shows the attractive backward wave propagation within the partial passband, thus introducing a novel waveguide-based artificial negative refractive index metamaterial (NRIM).