Terahertz (THz) links will play a major role in high data rate communication over a distance of few meters. In order to achieve this task, antenna designs with high gain and wideband characteristics will spearhead these links. In this contribution, we present different antenna designs that offer characteristics better suited to THz communication over short distances. Firstly, a single-element antenna having a dipole and reflector is designed to operate at 300 GHz, which is considered as a sub-terahertz band. That antenna achieves a wide impedance bandwidth of 38.6% from 294 GHz to 410 GHz with a gain of 5.14 dBi. Secondly, two designs based on the same dipole structure but with added directors are introduced to increase the gain while maintaining almost the same bandwidth. The gains achieved are 8.01 dBi and 9.6 dBi, respectively. Finally, an array of 1×4 elements is used to achieve the highest possible gain of 13.6 dBi with good efficiency about 89% and with limited director elements for a planar compact structure to state-of-the-art literature. All the results achieved make the proposed designs viable candidates for high-speed and short-distance wireless communication systems.

This manuscript demonstrates a comprehensive analysis of a low-profile dual-band flexible omnidirectional wearable antenna, designed for Wireless Body Area Network (WBAN) applications. The proposed antenna is designed and fabricated on a commercially available semiflexible RT/duroid 5870 substrate. The antenna prototype is composed of a circular radiating patch with a star-shaped slot at the center, providing dual-band operations that resonates at the 2.45 GHz ISM band and 5.2 GHz WLAN band. Meanwhile, two truncated arc-shaped slots at the top and bottom edges of the radiating patch and the partial ground were utilized to improve the reflection coefficients (S ₁₁ ) and impedance bandwidth of the antenna. The proposed antenna has a compact footprint of 47×30×0.787 mm ³ (0.38 λ0 × 0.25 λ0 × 0.006 λ0 at 2.45 GHz), with measured impedance bandwidth of 48% and 38.5% at 2.45 GHz and 5.2 GHz respectively. Moreover, the designed antenna has an omnidirectional and bidirectional radiation feature with the estimated gain of 2.5 dBi, 4.63 dBi and numerical efficiencies of 98.5% and 95% at 2.45 GHz and 5.2 GHz respectively. Furthermore, a comprehensive investigation encompassing a specific absorption rate and an exploration of bending aspects validated the effectiveness of the suggested design in adhering the SAR threshold and its remarkable robustness, when confronted with the demands imposed by human body loading and structural deformations. Consequently, both the numerical and measured results strongly endorse the significance of the suggested design for lightweight, body-worn wearable devices within the Wireless Body Area Network applications.

This paper presents the design of a rectangular microstrip line-fed patch antenna array with a centre frequency of 3.8 GHz for WiMAX and Unmanned Air Vehicle (UAV) applications. A single element, 1×2 and 2×2 microstrip rectangular patch antennas were designed and simulated in Computer Simulation Tool (CST) Microwave Studio environment. The results of designed antennas were compared in terms of Return Loss (S11 parameters), bandwidth, directivity, gain and radiation pattern. Compared to traditional microstrip antennas the proposed array structure achieved a gain and directivity of 13.2 dB and 13.5 dBi respectively. The antenna was fabricated using Rogers Duroid RT-5880 substrate with a dielectric constant e _r of 2.2 and a thickness of 1.574 mm respectively. The array antennas were measured in the laboratory using Vector Network Analyser (VNA) and the results show good agreement with the array antenna simulation.

This paper presents a novel quad-element array with multiple inputs and multiple outputs (MIMO) designed for 5th generation sub-6 GHz applications. The MIMO system achieves a wide impedance bandwidth, high gain, and high isolation among its components, representing significant advancements in sub-6 GHz antenna applications. The single element, an elliptical resonator with a circular slot, is fed by a 50 Ω microstrip feedline, achieves a broad characteristic bandwidth from 3.7 to 5.7 GHz with a resonant frequency of 4.33 GHz and a gain of 1.81 dBi. Characteristic Mode Analysis (CMA) was employed to elucidate the evolution phases of this design. The quad-element MIMO antenna array maintains a compact size and broadband characteristics by arranging mirrored elements on the same ground plane. Implemented on a cost-effective FR-4 substrate measuring 44 × 44 × 1.6 mm³, the recommended MIMO antenna array, enhanced with a partial ground plane and due to the introduction of a vertical strip, a high isolation of − 38.53 dB is achieved between MIMO components along with a realized gain of 3.01 dBi and a radiation efficiency of 71% in the 5G sub-6 GHz band. Noteworthy properties include high isolation, diversity gain (DG), and envelope correlation coefficient (ECC), verifying the appropriateness of the suggested MIMO scheme for 5G transmission and reception in sub-6 GHz applications.