GHz For Wi-Fi Applications Research Articles

Compact multi-standard planar MIMO antenna for IoT/WLAN/Sub-6 GHz/X-band applications

A compact six-element MIMO antenna is presented for present and future wireless applications. The resonating elements of the proposed antenna are simple monopoles, which are excited by microstrip feed lines. In the MIMO antenna, two elements (Ant. 1 and Ant. 2) cover 727–1066 MHz and 5.28–6.2 GHz frequency bands for the IoT and WLAN/Wi-Fi applications, respectively. The other two elements (Ant. 3 and Ant. 4) cover 1.7–1.9 GHz band for NB-IoT applications, 5.5–5.8 GHz for Wi-Fi applications and 7.2–8.9 GHz for X-band applications. Other two elements (Ant. 5 and Ant. 6) cover 3.1–3.58 GHz band for sub-6 GHz applications. Decoupling network and stubs are used for isolation and impedance matching in the proposed MIMO antenna. The antenna shows a decent gain in all the resonating frequency bands.

On the design of a reject band filter for antennas mutual coupling reduction

In this article, a novel concept for mutual coupling reduction between antenna elements is proposed at 2.45 GHz for Wi-Fi applications. A reject band filter (RBF) is used in order to reduce the mutual coupling between two monopoles for multi-input multi-output (MIMO) systems. The proposed RBF inclusions are developed to have zero refractive index response over a specific frequency band. The inclusions considered here are composed of open-loop resonators; each one with the same iteration level of Minkowski-like pre-fractal structures coupled with an open-stub transmission line to increase the band selectivity. The inclusions are inserted between λ/2-spaced monopole elements at 2.45 GHz. A significant mutual coupling reduction is realized by incorporating only two RBF cells. Such effective response is attributed to the electromagnetic wave cloaking at 2.45 GHz using the developed RBF inclusions. An extensive theoretical study using both numerical and analytical methods is invoked to obtain the best performance of the proposed MIMO antenna structure. Finally, the experimental and numerical results are agreed excellently.

OPTICALLY TRANSPARENT COMPACT 4×4 BUTLER MATRIX FOR WI-FI APPLICATIONS

In this paper, an optically transparent (OT) compact 4 × 4 Butler matrix (BM) operating at 2.4 GHz for Wi-Fi applications is proposed. The device has structured grids refined in quadrilateral cell shapes. The dimensions of cells are chosen based on a simple formula which guarantees a minimum required transparency level in conjunction with a limited rounds of optimizations. A theoretical optical transparency value of 76.2% has been obtained without affecting the excellent electrical performance of the BM. Moreover, complimentary square split ring resonators (CS-SRRs) are patterned in the ground plane of each transparent transmission line in the BM. This loading technique provides a relative size reduction of 16.6% compared to a conventional structure. Simulated and measured results of the proposed design agree well with conventional BM's results. The proposed technique and its related features can be expanded to other microwave devices.