This letter presents a compact triple-band antenna composed of a spiral radiator with an open-ended slot at the ground for human head-implantable wireless communications. It operates simultaneously at a Medical Implant Communications Service (MICS) band (402-405 MHz), a Wireless Medical Telemetry Service (WMTS) band (1427-1432 MHz), and an Industrial, Scientific, and Medical (ISM) band (2400-2480 MHz). The proposed antenna has a thin profile of 0.5 mm with a volume of 197 mm ³ . Semisolid phantoms are used for the design and experimental validation, and detailed parameter studies are carried out to determine the working principles of the antenna. Based on simulations and measurements, it was found that the proposed antenna covers all the desired frequency bands with comparably high boresight gains given its compact dimensions.

The art of paper folding also known as Origami plays an important role in various research areas of different scientific fields. Origami structures possess many useful characteristics such as reconfigurability, flexibility, deployability, compactness, and multi-functionality. These attributes are inevitable for modern communication systems. Additionally, they provide antenna engineers an extra degree of freedom while blueprinting next-generation designs. One of the desirable features of origami is its folding capability. Using this property, it can be transformed into a two-Dimensional (2D) sheet from a three-Dimensional (3D) structure and vice versa through external stimulus. In recent years, researchers have proposed numerous smart materials to optimize folding behavior. These smart materials extend the functionality of origami technology for designing self-folding structures required in space systems, small scale devices, and self-assembly systems. Origami structures feature many useful characteristics pertinent to modern day design challenges of communication systems such as reconfiguration, flexibility, compactness, and multifunctionality. In this work, a state of the art review is presented on conceptualization, design challenges, and fabrication of light-weight and low-cost deployable origami antennas. Furthermore, to provide critical insights deployment challenges and possible solutions are also provided. It is believed that this work will not only help peers to understand the basic working principles of different origami structures but will also lay the foundation for future research in the evolving field of origami-based antennas. Moreover, the design methodology proposed in this paper will also provide pragmatic solutions for origami antennas suitable for the harsh and rigid environments.

We propose a deployable quasi-Yagi monopole antenna using origami magic spiral cubes, constructed from low cost paper substrate. The proposed quasi-Yagi antenna consists of an L-shaped driven monopole, an L-shaped reflector, and two L-shaped directors. These driven monopole, reflector and directors are designed in L-shaped geometries to achieve maximum gain in a limited cube size. The driven element and reflector are realized on the origami magic cube #1, while the two directors are designed on the magic cubes #2 and #3, respectively. The cubes are stacked together using a thin adhesive film. The presented geometry of the origami magic spiral cube antenna can be easily folded and unfolded. The dimensions in the unfolded state are 44 mm × 44 mm × 132 mm while the dimensions in the folded state are 44 mm × 44 mm × 8 mm. Therefore, in the folded state, the antenna occupies only 6% of the unfolded volume. We have numerically analyzed the antenna performance and verified the outcomes experimentally. The L-shaped reflector has increased the monopole antenna gain from 1.9 to 5.7 dBi. With the addition of two directors, the gain is further increased to 7.3 dBi at 1.9 GHz.

A novel design of an electrically small, dual-band quasi-isotropic antenna with a microstrip balun is presented. A quasi-isotropic radiation pattern is realized from the total current flow over the proposed structure at two different frequency bands. The electrical size ka of the antenna is 0.49 with an extremely thin profile of 0.0014g. The antenna measurements reveal good uniformity of the radiation pattern with a maximum gain deviation of 5.83 dB at 942 MHz and 8.24 dB at 1.71 GHz with 57% and 95% radiation efficiency, respectively. The radiation performance of the antenna is also verified through wireless power receiving experiments in an office non-line-of-sight environment.

This article presents an extensive examination of antennas rooted in nature and biology, showcasing their remarkable performance across a wide spectrum of frequencies—from microwave to terahertz. The limitations of traditional antenna design have become increasingly evident in the face of burgeoning demands for novel communication technologies. Conventional analytical-equation-based approaches struggle to deliver the combined performance characteristics – encompassing bandwidth, gain, radiation pattern, and miniaturization – that emerging technologies necessitate. This has fueled an interest in bio-inspired antenna designs, a paradigm shift drawing inspiration from the ingenious structural solutions found in the living and non-living world, from plant leaves to bird feathers. These bio-inspired designs offer distinct advantages such as broader bandwidth and reduced sizes, making them highly appealing alternatives to the limitations of conventional antenna designs. This review explores a diverse range of bio-inspired designs. Among them are fractal geometries, inspired by self-repeating patterns in nature, which achieve optimal performance. Numerous designs in this category draw inspiration from nature, incorporating patterns observed in snowflakes, tree branches, clouds, and butterflies. Furthermore, nano-antennas have attracted significant attention for their vast potential applications in microwave and optical frequencies, playing a pivotal role in high-resolution spectroscopy, biomedical diagnosis and sensing, quantum photonics, and solar cell applications. By examining design methodologies and potential benefits, this article highlights the transformative potential of nature-inspired antennas. The compelling advantages of bio-inspired approaches necessitate a thorough exploration of their potential, paving the way for the development of next-generation communication systems with unprecedented capabilities.

In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN) applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900–1120 MHz) and 15% (2.1–2.45 GHz) for the unfolded state and 20% (1.3–1.6 GHz) and 14% (2.3–2.5 GHz) for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state.