Miniaturized shared aperture multiband antenna for wireless biomedical applications

RESEARCH ARTICLE Miniaturized shared aperture multiband antenna for wireless biomedical applications Abdul Rehman Chishti 1*, Abdul Aziz1, Muhammad Nawaz Abbasi1, Khaled A. Aljaloud2*, Ali H. Alqahtani2, Rifaqat Hussain3 1 Department of Information and Communication Engineering, Faculty of Engineering, The Islamia University of Bahawalpur, Bahawalpur,‌‌ Pakistan, 2 College of Engineering, Muzahimiyah Branch, King Saud University, Riyadh, Saudi Arabia, 3 Antenna and Electromagnetics Research Group, School of Electronic Engineering and Computer Science, Queen Mary University of London, ‌‌London, United Kingdom * (ARC); (KAA) Abstract OPEN ACCESS Citation: Chishti AR, Aziz A, Abbasi MN, A Aljaloud K, Alqahtani AH, Hussain R (2026) Miniaturized shared aperture multiband antenna for wireless biomedical applications. PLoS One 21(6): e0349676. https://doi.org/10.1371/ journal.pone.0349676 Editor: Muhammad Zubair, University of Leicester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND Received: September 20, 2025 Accepted: May 4, 2026 Published: June 4, 2026 Copyright: © 2026 Chishti et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data availability statement: All relevant data are included within the paper. Funding: The author(s) received no specific funding for this work. This study presents a compact, folded dipole multiband shared-aperture antenna that operates effectively across both sub-1 and sub-6 GHz frequency bands using a single radiating structure—constructed on an FR-4 substrate. Design measures 16.40 × 10.50 × 1.52mm3 ( 0.0386λ × 0.0247λ × 0.0036λ ), ( 0.431λ × 0.276λ × 0.040λ ), ( 0.512λ × 0.328λ × 0.048λ ), resonates at the bands of 0.431-0.435 GHz, 4.75-4.96 GHz, and 5.64-5.88 GHz, thus having a flexibility to a wide range of applications. The proposed antenna is a folded dipole built on the upper layer, and the coaxial feeds run to horizontally and vertically oriented strips on the backside layer. This arrangement enables simultaneous use along with various frequency bands in a single physical structure by taking advantage of shared-aperture concept thereby achieving space economy and operational efficiency. By applying a miniaturization plan based on lumped element integration, the radiating system guarantees a reduction of 80% in the dimensionality, and remains functionally intact. Besides, the integrated measurement subsystem incorporates a cancer-related analyte which mimics the electromagnetic nature of cancerous cellular organisms and thus a detectable spectral change at 5.7 GHz. The implication of this phenomenon is the initiation of an oncogenic presence diagnostic indicator. The concomitant capability of operating in multiple bands and smaller footprint make the antenna especially favourable to use in the context of operating in healthcare infrastructures for biomedical platforms along with wireless communication applications. Introduction Antennas are an important part of modern world of wireless communication [1–5], especially 5G communication. Working in specific frequencies, they maintain constant connections of the devices in different settings, at home, at workplace, or on the PLOS One | https://doi.org/10.1371/journal.pone.0349676 June 4, 2026 1 / 17 Competing interests: NO authors have competing interests. move. Recent advancements like MIMO and beamforming improve signal strength and reliability even more, particularly in cities with a large population density with numerous devices competing to get the communication resources. The recent developments in antenna design have greatly expanded its use, extending well beyond the old-fashioned communication roles and making notable discoveries in the field of biomedical uses [6,7]. Theoretical uses includes automotive systems with antenna-based systems upon them [8], satellite platforms and other systems with antennas on them [9–11], biomedical environments and aircraft aboard them respectively. Antennas used in the biomedical context not only transmit information, but also facilitate information tracking, surveillance, and other applications, as well as monitoring capabilities [12–14]. Designing a miniature antenna is also essential since it can be fitted easily in small gadgets. The electrically small antennas (ESA) is a result of miniaturization of the antenna. Such a design however requires certain technologies and the corresponding impedance-matching network that is dependent on the application [15]. The inverse relationship between Q factor and antenna bandwidth has a negative impact on ESA as it is limited in bandwidth. Further, the setback is due to matching of impedances, thus nullifying the overall ESA performance. First, the antennas were placed side by side to induce the behavior of multiband antennas. The novelty in this design is that a common aperture of an electrically small antenna has been implemented, an important breakthrough in small antenna designs. The shared aperture allows shared physical space to be used by various radiating elements or functions, allowing other frequency bands or functionalities to share the aperture. This is done by decreasing the size and complexity of the antenna in general but maintains multiband operation. In the case of electrically small antennas where space is the most important factor, such a technique is the best way to maximize the use of space without reducing performance. Two or more antennas at different frequency bands are separately fixed into one radiating topology in a shared aperture which subsequently provides a compact form factor, high efficiency, and reduced mass, which has been reported by [16,17]. The combination of two or more antennas in a common aperture faces challenges of the spatial distance between the antennas and the dimensions of the radiating elements. To address these challenges while maintaining a compact design, microstrip antennas are often preferred for their low mass and ease of integration with the feeding network. Most designs of shared aperture antennas have focused on applications suitable for 5G technology [18], particularly in the sub-6 GHz and mm-wave bands. For biomedical application recommended bands include 433–434MHz, 608– 614MHz, 868-868.6MHz, 902.9-928MHz, 1395–1400MHz, 1427–1432MHz and 2.42.5GHz [19]. For 5G communication, new bands are added that include sub-6 GHz and millimeter-wave to achieve wireless communication with higher capacity [20,21]. Related work Authors in [22] have designed a folded dipole operating at a 2.4 GHz band using multiple lumped elements, where frequency shifting at sub-1 GHz was achieved. PLOS One | https://doi.org/10.1371/journal.pone.0349676 June 4, 2026 2 / 17 Multiple lumped elements bring complexity to the design, and designing such an antenna is tedious. (...truncated)