Boddapati Taraka Phani Madhav

A compact, inverted L-stub multiband antenna measuring 21x16x1.6 mm3 was constructed on Rogers 5880 substrate. The antenna is made to work with smart devices that need to connect to the IoT, 5G networks, and aeronautical mobile telemetry (AMT) applications. The proposed model provides bandwidths of 170 MHz (4420 to 4590) MHz, 890 MHz (5010 to 5900) MHz, and 120 MHz (5740 to 5860) MHz. The proposed antenna exabits a wide bandwidth of 10. dB from 4.42 - 4.59 GHz, 16.3% from 5.01 to 5.90 GHz, and 2.01% from 5.74 - 5.86. GHz, offers a peak gain of 6.81 dBi at 5.7 GHz, an average efficiency of 83.2%, and it also operates at 4.48 GHz & 5.04 GHz.

The design, fabrication, and testing of an optically transparent wideband antenna for 5G, wireless body area networks (WBAN), and ultra-wideband (UWB) applications below 6 GHz using indium-tin oxide (ITO) as the radiating material are covered in this study. The antenna setup includes a circular monopole radiator, a fractal loading arrangement, and a modified coplanar waveguide (CPW) ground construction. The antenna is made on a transparent substrate that is covered with an ITO conductive coating to keep it from blocking light. The proposed structure exhibits transparent characteristics, with typical optical transmittance of ITO films reported in the range of 80–90% in the visible spectrum. The observed −10 dB impedance bandwidth spans a broad frequency range from 1.45 to 11.6 GHz. At 1.65 GHz, 5.8 GHz, and 9.7 GHz, there are well-defined resonances with reflection coefficients of −32.8 dB, −22 dB, and −37.6 dB, respectively. This shows that the impedance is well-matched. The antenna has a gain of 6.0 to 6.2 dB at 6.1 GHz and maintains gains of more than 4 dB across most of the working spectrum. Testing for mechanical bending demonstrates that stable performance is possible up to a bending angle of 45°, with the worst-case S₁₁ staying better than −11 dB A time-domain study shows that the group delay changes by less than 1 ns, which means that the signal is not distorted much in the process innovation. Also, the maximum specific absorption rate (SAR) for 1 gm. of tissue attained is less than 0.39 W/kg, which is in conformity with FCC safety rules. The transparent antenna has a broad bandwidth, high efficiency, strong mechanical structure, and outstanding optical transparency.

This article presents a compact UWB monopole antenna based on a decagonal ring, in which a set of fractal‐inspired slots is introduced to broaden the operating bandwidth while maintaining a compact structure. These slots are added primarily to increase the electrical path without increasing the overall radiator size, thereby making the antenna easy to integrate when space is limited. A prototype is fabricated on a standard FR4 substrate with dimensions of 40 × 30 × 1.6 mm ³ . The proposed design is first optimized using full‐wave simulations and then experimentally tested. The antenna operates continuously from 2 GHz up to 11.20 GHz, with a peak gain of about 5.5 dBi and a radiation efficiency close to 95.6%. Simulated and measured results show a satisfactory agreement over the whole operating range. Besides the wide frequency span, the antenna also maintains stable radiation patterns and satisfactory time‐domain behavior, often challenging to obtain in compact UWB designs. Its compact footprint and simple fabrication make easy integration into different wireless systems. Owing to its compact, optimized design, wideband performance, excellent time and frequency domain characteristics, low cost, and ease of fabrication, the proposed antenna can therefore be used in IoT nodes, low‐power wireless connections, Wi‐MAX system, and several UWB sensing scenarios operating in Sub‐6 GHz, C‐band, and parts of the lower X‐band spectrum.

In this article, ultra‐wideband (UWB) single‐element and two‐port multiple‐input‐multiple‐output (MIMO) antenna structures with circular polarization (CP) characteristics are designed to support numerous modern wireless systems. The basic CP element is designed to obtain an ultra‐wide operating bandwidth. In the design process, a circular stub is integrated into the ground plane, and a circular slot is structured into the patch to achieve CP. On the other hand, a rectangular stub is used to improve the axial ratio bandwidth (ARBW). The elemental antenna achieves an impedance bandwidth (IBW) of 97.96% (4.13–12.06 GHz), an ARBW of 49.62% (5–8.3 GHz), a peak gain of 5.75 dB, and a minimum efficiency of 80%, maintaining small dimensions of 20 mm 20 mm 1.6 mm (0.275 λ ₀ × 0.275 λ ₀ × 0.022 λ ₀ ). Meanwhile, a two‐element UWB MIMO radiator of 20 mm 44 mm 1.6 mm (0.275 λ ₀ × 0.606 λ ₀ × 0.022 λ ₀ ) is designed and experimentally validated. It addresses the challenges of achieving wide impedance and axial‐ratio bandwidths while maintaining a compact size and high isolation for MIMO operation with attractive diversity performance. It achieves an impressive ultrawide IBW of 100% (4–12 GHz), ARBW of 42.73% (4.6–7.1 GHz), and 10.90% (7.8–8.7 GHz) while offering improved isolation. The MIMO geometry exhibits outstanding diversity performance, with an envelope correlation coefficient (ECC) < 0.01, diversity gain (DG) > 9.92 dB, total active reflection coefficient (TARC) < 10 dB, and channel capacity loss (CCL) < 0.2 bits/s/Hz. These features render the proposed UWB MIMO antenna exceptionally appropriate for various wireless communication uses, such as microwave C‐band (4–8 GHz), WiMAX (5.725–5.850), WLAN (5.150–5.825 GHz; 5.925–7.125 GHz), and satellite communication in X‐band (downlink: 7.25–7.745 GHz and uplink: 7.9–8.4 GHz).

To address the issue of satisfying absorption levels in the microwave X-band region, this study proposes a tri-band metasurface absorber that makes use of a new non-uniform technique. A unit cell is used to form the proposed absorber. This unit cell is printed on a jeans dielectric substrate, which has a dielectric constant of 2.2. copper material is chosen as a radiating patch for the proposed unit cell. The radiating patch contains different polygons with different sizes. The structure has been designed in four phases to have three absorption peaks. The structure that is being proposed is resonating at three different resonant frequencies, which are 9.98GHz, 10.43GHz, and 11.30GHz. Irrespective of polarization angles and mode of propagation, the structure produced absorptances as 95.1, 97.3, and 99.89, respectively for the corresponding resonant frequencies. The absorber that has been proposed possesses an electro-magnetic characteristic that is effective for microwave applications, particularly for satellite and radar telecommunications. Additionally, bending analysis confirms the robustness of the design under conformal conditions, making it suitable for practical X-band applications such as radar cross-section reduction, satellite communication systems and electromagnetic interference mitigation. This work contributes to SDG 9: United Nations Sustainable Development Goal 9 by advancing innovative, flexible electromagnetic absorber design for next-generation X-band applications.