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This paper presents an ultra-miniaturized skin implantable Multiple Input Multiple Output (MIMO) antenna for biotelemetry in the Industrial, Scientific, and Medical (ISM) band (2.4–2.48 GHz). The two-element configuration exhibits a compact planar volume of 4.5 × 6.2 × 0.25 mm³, with an edge-to-edge distance of 0.8 mm and a 75.85 % size reduction. Fabricated on a 0.25 mm thick Roger 10.2LM high permittivity substrate, the antenna achieves a Fractional Bandwidth (FBW) of 9.27 % and a realized gain of −28.2 dBi, with over 24.3 dB isolation across the entire band. Experimental results in multilayer animal tissue aligned well with simulations. Specific Absorption Rate (SAR) analysis at 1 W input power showed values of 848 W/kg (1-g) and 88.46 W/kg (10-g), yielding allowable input powers of 3.77 mW and 45.2 mW, respectively, adhering to international safety guidelines. The 2 × 2 element antenna demonstrated efficient communication over 7 m with a data rate of 78 Mbps/s. Multiple Input Multiple Output channel analysis revealed a Channel Capacity of 10.8 bps/Hz at a 20 dB SNR, nearly double that of an ideal Single Input Single Output system, making it suitable for high data rate skin-implantable applications.

Wireless body-centric communication technology has experienced substantial growth in the wearable device industry, owing to the growing demand for remote health monitoring, military and sensing applications, etc., without compromising the wearer’s comfort. This growth is aided by the popularity of wearable antennas for their beneficial features such as low profile, adaptability, durability, and biocompatibility with specific absorption rate (SAR), which make them viable options in wireless body area network (WBAN) deployments. This study introduces a modified T-shaped, stub-loaded planar antenna tailored for wearable applications across WiFi (2.08–2.88 GHz), WLAN (3.55–5.4 GHz), and WiMAX (5.73–5.92 GHz) bands. Leveraging strategically placed slits/stubs, additional resonances are introduced to achieve multiband functionality. This design features a via-less structure, facilitating simplified fabrication process. The effectiveness of the antenna is validated by simulation and equivalent circuit modeling. Bending analysis based on human body radii shows minimal performance deterioration, exhibiting equivalent performance when both flat and bent at 30- to 80-mm radii. The antenna offers a low SAR without introducing additional SAR reduction techniques. SAR values of 0.184, 0.1936, 0.4981, 0.6531, and 0.7339 W/kg were achieved at operating frequencies of 2.45, 3.77, 4.66, 5.23, and 5.83 GHz, respectively, which ensures adherence to safety guidelines. The sensitivity of the antenna sensor is also investigated for different volumes of a tissue model through resonant frequencies shift at varying distances. Moreover, the antenna is demonstrated by experimental validation, which includes wrist placement and gesture recognition trials.

This article presents a compact implantable antenna for biomedical use in the ISM band (2.4–2.48 GHz). The antenna is designed with Roger RT/duroid 6010.2LM high permittivity substrate of thickness 0.25 mm, and feed with a 50 Ω co-axial feed. A hybrid-loop resonator slot structure and C & I-shaped slots in the radiating patch has enabled the antenna to work in the ISM band. Via less ground makes this design simple, easier to fabricate, and a suitable candidate for implantable application. The proposed antenna occupies a small volume of 0.0984 λ0× 0.082 λ0× 0.00468 λ0and retained 152 MHz bandwidth (2.4077–2.5599 GHz with FBW 7.64 %) with a maximum gain of −22 dBi where λ0is guided wavelength. The projected antenna has good performance in the multi-layer tissue model, male human head voxel model, frequency-dependent skin model, and in muscle phantom by maintaining a minimum −20 dB return-loss in the ISM band. The proposed antenna’s Device Integration using a frequency-dependent skin phantom was performed and the results are well-suited for biomedical applications in the ISM band. The bare antenna was used to study the Specific Absorption Rate (SAR) in the human scalp. Where for 1 g and 10 g tissues the investigated results are 626.05 W/kg and 84.4 W/kg for an input power of 1 W, however the input power is limited to maximum 2.55 mW (for 1 g tissue) and 23.56 mW (for 10 g tissue) to comply with IEEE SAR guidelines. The qualities of the manufactured antenna are verified in a skin-imitating gel and animal tissue that exhibits good agreement with the simulation outcomes.

A two-port multiple input multiple output (MIMO) dielectric resonator antenna is proposed where two orthogonally connected feed lines are combined to unite two orthogonally produced modes. The feed lines build a hybrid network. The backplane is defected by a circular defected ground structure (CDGS), which is extended by two rectangular slits placed orthogonally with the input ports. The antenna uses a single ‘H/I’-shaped dielectric resonator (DR) element. It covers frequency spectrum from 7.29 to 10.65 GHz and fulfils the international telecommunication union (ITU) (8–8.5 GHz) and Maritime Radio Navigational (8.85–9 and 9.2–9.5 GHz) application bands. The antenna offers very high port isolation (>18 dB) and diversity properties throughout the whole application band. The antenna also provides circular polarization (AR ≤ 3 dB) in the operating ranges from 8 to 8.25 GHz and 8.85 to 8.9 GHz. Simulated and measured results make clear to the antenna most suitable for MIMO operation.

This paper presents a detailed design and realization of a switched‐beam network. The concept is verified using planar microstrip technology. Beam forming network is constructed by a 4 × 4 Butler matrix on a single‐layer substrate. The proposed design is centered at 5.5 GHz (C‐band) for commercial WLAN applications. Individual components of the Butler matrix are discussed here and further integrated system analysis is outlined in this article. The whole architecture is realized on low‐loss FR4 substrate. Design aspects, measured results and comparative study are summarized here. Planar, switch beam, Butler matrix, wireless communication Planar, switch beam, Butler matrix, wireless communication