This work presents a low-cost, easy-to-fabricate, kirigami-inspired deployable MIMO antenna operating at 2 GHz, featuring dual polarization and angular pattern diversity. Inspired by the Yagi antenna design, the proposed MIMO antenna comprises two orthogonally oriented antennas, each consisting of a rectangular radiating element (monopole) and one parasitic rectangular strip (director). These are integrated onto a foldable, staircase-shaped Kirigami structure made of polyethylene terephthalate (PET) sheet. Each antenna includes a reflector attached to the Kirigami structure’s back. Operating at 2 GHz, the antenna achieves a measured peak gain of 9 dBi with a -10 dB impedance bandwidth of 630 MHz (1.82 GHz to 2.45 GHz). Mutual coupling between the radiating elements is maintained below -15 dB, and the total efficiency exceeds 80% across the operating band. The antenna system meets MIMO specifications, demonstrating an Envelope Correlation Coefficient (ECC) below 0.0025 and a Channel Capacity Loss (CCL) below 0.35 bps/Hz. This combination of high performance, low cost, and ease of fabrication makes the proposed design a promising candidate for diverse microwave applications.

Full-wave electromagnetic (EM) simulation, particularly in environments such as CST Studio Suite, makes large-scale antenna optimization computationally prohibitive. We introduce an adaptive surrogate-assisted differential evolution (DE) framework, implemented via a unified CST-Python workflow, designed to accelerate design-on-demand antenna optimization. The workflow integrates target-frequency-driven design requests, multimetric antenna performance targeting, cross-validated surrogate selection, selective CST validation, and iterative CST-verified dataset updating. It begins with Latin hypercube sampling (LHS) to create a CST-simulated training set, selects a regressor (KNN, RF, SVR, GB, XGBoost) via five-fold cross-validation based on mean squared error, and then uses the surrogate to guide the DE search. The core adaptive mechanism involves mandatory full-wave validation of the best design candidate from each optimization cycle, appending the verified result to the training dataset to enable targeted model refinement. Optimization is governed by a multiobjective penalized aggregate function that minimizes the resonant-frequency error while maximizing the design performance metrics of bandwidth, return loss, and gain. We evaluated this approach on three antenna families-dipole (2.00 GHz), microstrip patch (2.55 GHz), and Yagi-Uda (2.50 GHz)-and met targets with only 10-12 full-wave validations per run. Our method achieved a verified design in 9-16 min, whereas pure DE took 21-113 min with 28-55 full-wave solves, and pure PSO took 18-217 min with 28-106 full-wave solves. This corresponds to speedups of 2.38-8.06 & times; and 2.04-13.68 & times;, respectively. This work demonstrates that integrating an adaptively selected surrogate model into the optimization strategy substantially reduces the computational cost of full-wave analysis, establishing a highly efficient and robust methodology for diverse EM design applications.

This paper presents a novel deployable antenna design with reconfigurable radiation patterns suitable for various indoor Internet of Things (IoT) applications. Inspired by origami, the antenna comprises a central monopole patch housed on a magic cube (MC-2) and two other modular units comprising stacks of magic cubes (MCs). In compact form, i.e., State-1, the antenna occupies a space of 50 mm, whereas in other states, it occupies a maximum of 150 mm space. Pattern reconfigurability is achieved by simply folding or unfolding these units. The antenna operates in four different states. For example, when both MC-1 and MC-3 are folded, the antenna exhibits an omnidirectional pattern (State-1). When either MC-1 or 3 are folded, the antenna shows directional behavior (States 2 and 3), offering ± 90° beam switching, whereas when both MC-1 and 3 are unfolded, the antenna exhibits bidirectional behavior (State 4), directing the main beam toward 88° and 92°. The antenna operates in the 2 GHz band and exhibits peak gains ranging from 2 dBi to 9 dBi. The excellent agreement between the simulated and measured results validates the design. This cost-effective, reconfigurable antenna presents a promising solution for diverse indoor IoT applications because of its cost-effectiveness and reconfigurable nature.

This paper presents the design, optimization, and performance analysis of a compact four-port ultra-wideband (UWB) MIMO antenna for next-generation high-frequency communication systems. The antenna is built on a Rogers RT Duroid 5880 substrate and operates effectively in the 12.5–55 GHz, range making it suitable for millimeter-wave 5G applications. A four-step design process is used to develop a single antenna element optimized for wide bandwidth and good impedance matching. Parametric studies on feedline length, inset depth, and ground structure help improve bandwidth and ensure strong radiation patterns. In the MIMO setup, four radiating elements are placed at right angles to each other to reduce mutual coupling. Additionally, a centrally located plus- shaped decoupling resonator is added to further improve isolation, especially at lower frequencies, enhancing overall antenna performance. Simulation results show excellent impedance matching, a very low envelope correlation coefficient (ECC < 0.004), and a high diversity gain (dB). The antenna also delivers stable radiation patterns and high efficiency (>85 %) across the operating range. These findings confirm that the proposed MIMO antenna offers strong isolation (<-20dB), compact size (20x20 mm2), and wide bandwidth (40GHz) making it a suitable choice for future UWB and millimeter-wave MIMO systems.

In modern communication systems, ultra-wideband (UWB) technology has garnered substantial attention due to its superior attributes compared to traditional narrowband communication systems. Over the past decade, UWB technology has also found applications in microwave-based imaging systems. This study introduces a simple planar coplanar waveguide-fed circular shape arc slot antenna designed specifically for biomedicine and microwave medical imaging applications. The proposed design is implemented on a 1.6-mm-thick FR4 substrate with a relative permittivity of 4.4 and a loss tangent of 0.0009. The antenna has physical dimensions of 26 mm × 29 mm and achieves an impressive bandwidth of 16.6 GHz, spanning 2.4 to 19 GHz. It exhibits a peak gain of 2.5 dBi and consistent omnidirectional radiation characteristics. Thorough temporal analysis validates the antenna's performance within acceptable limits, which is further affirmed through practical fabrication and testing, demonstrating strong agreement with simulation results.

The purpose of this chapter is to recall origami technology, outline its properties and applications, as well as discuss its attractive features in the context of contemporary engineering. The main part of the chapter focuses on origami antennas. We juxtapose these and traditional antenna systems and introduce the basic types of origami antennas from the point of view of their implementation. We discuss single- and multi-paper-based structures, PET-based antennas, origami antennas realized on conventional substrates, and well as those manufactured using the inkjet and 3D printing technology.

Origami antennas are versatile and flexible devices that can be folded into various shapes and sizes. This unique feature makes them highly portable and easy to deploy in various environments, ranging from military operations to satellite communication and energy harvesting applications. This chapter will explore the numerous practical applications of origami antennas in these fields and more. From their lightweight and compact design to the ability to capture and convert electromagnetic energy, we will examine the benefits and limitations of origami antennas in various scenarios. Upon reading this chapter, readers will have a better understanding of the practical uses and potential of origami antennas in today’s world.

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.

The purpose of this chapter is to provide a comprehensive introduction to the design process of origami antennas. These antennas are designed using the same principles as conventional structures but with an added focus on robustness and deployability. To create a functional origami antenna, conductive and dielectric materials are required, along with careful material and design selection to meet specific application requirements. The origami design process involves the transformation of a flat surface into a three-dimensional structure, enabling it to cover more surface area and increase its performance. Early origami antenna designs relied on manual deployment, which was not practical for real-world systems due to the increased complexity and performance limitations associated with folding and unfolding. To address these issues, self-deployment methods using actuators were investigated to reduce design complexity and to improve the overall antenna performance. The employment of origami-based structures has opened new possibilities for developing antennas with improved functionality and portability. By utilizing the folding and unfolding capabilities of origami, antennas can be manufactured to occupy minimum space during transportation and storage and deployed with ease when required. Moreover, origami antennas offer a cost-effective solution for a range of applications, including space exploration, communication systems, and military operations. These antennas can be easily folded and transported to remote locations, making them ideal for emergency communication and disaster response efforts. In this chapter, we outline the design process of origami antennas and how it combines traditional antenna design principles with careful material and design selection to achieve robustness and deployability.

Microwave medical imaging (MMI) is experiencing a surge in research interest, with antenna performance emerging as a key area for improvement. This work addresses this need by enhancing the directivity of a compact UWB antenna using a Yagi-Uda-inspired reflector antenna. The proposed reflector-loaded antenna (RLA) exhibited significant gain and directivity improvements compared to a non-directional reference antenna. When analyzed for MMI applications, the RLA showed a maximum increase of 4 dBi in the realized gain and of 14.26 dB in the transmitted field strength within a human breast model. Moreover, it preserved the shape of time-domain input signals with a high correlation factor of 94.86%. To further validate our approach, another non-directional antenna with proven head imaging capabilities was modified with a reflector, achieving similar directivity enhancements. The combined results demonstrate the feasibility of RLAs for improved performance in MMI systems.

The world of wireless communication is buzzing with activity. The demand for new and innovative ways to transmit and receive data has been growing at an exponential rate, and the need for pattern reconfigurable antennas is becoming increasingly evident. Traditional antennas are limited by their fixed frequencies and radiation patterns. This can be a major drawback in applications that require dynamic and flexible radiation patterns, such as radar, satellite communication, and mobile networks. Origami technology offers a promising solution to this problem. By folding and unfolding origami structures, it is possible to create antennas with a wide range of radiation patterns. This makes them ideal for use in modern communication systems, where adaptability and efficiency are of paramount importance. In this chapter, we explore the use of origami technology to create pattern reconfigurable antennas. We discuss the basic principles of origami and how they can be applied to antenna design. We also present some of the latest research in this area, and we discuss the potential applications of origami antennas in future communication systems.

This paper proposes an enhanced bandwidth microstrip patch antenna by exciting it with higher order modes. Characteristics Mode Analysis (CMA) is used to analyze and understand the possible modes for bandwidth enhancement of microstrip patch antenna. Furthermore, Defected Ground Structure (DGS) technique is utilized for bandwidth enhancement. The proposed antenna is having a size of 67.5 × 67.5 mm2with an operating frequency of 5.8 GHz. The impedance bandwidth is increased by 13.8% using Defected Ground Structure (DGS) by adding slots in the ground for higher order mode operation. Moreover, the proposed antenna has an overall efficiency of above 80. Therefore, enhanced impedance bandwidth, improved radiation pattern, and compatible design make the design novel and suitable for practical wireless applications.

AbstractAn antenna array having a size of 45 $$\:\times\:$$ 40 cm2 (5.7 $$\:\times\:$$ 5 $$\:{\lambda\:}_{0}$$2) and consisting of four pairs of printed U-shaped dipoles positioned above a metal reflector, for 5G Sub-6 GHz base station applications, is designed and tested. The array consists of eight excitation ports, one port for each dipole. Four parasitic square patches are etched on the bottom side of the dipole arms for producing radiations in 2.2 GHz and 3.8 GHz bands. The size of the reflector and height of the dipoles are optimized in order to enhance antenna gain up to 11.5 dB at 2.2 GHz and 14.5 dB at 3.8 GHz. Beam steering up to 20$$\:^\circ\:$$ is achieved, using phase shifted simultaneous excitation of different ports. The proposed antenna array not only fulfills 5G base station requirements but is also simple and compact as it only requires eight ports to achieve dual-band, high-gain and beam steering operation in a single design. It also offers a unique feature of dual-sector coverage per panel, which results in an increased coverage capacity of the base station without increasing the system resources.

Origami antennas offer a lightweight, low-cost, and deployable alternative to traditional antennas for applications requiring mobility and quick deployment in harsh environments. Origami folding enables antenna miniaturization, making them ideal for space and planetary applications, as well as for communication applications that require large-sized antennas. For example, a deployable origami antenna in the microwave frequency range could be used for military communications. While traditional walkie-talkie-type units are susceptible to tapping and have a limited range, origami antennas can be easily transported and deployed in remote areas. Satellite communication is another option, but conventional satellite antennas are bulky and require large vehicles or helicopters to transport. Origami antennas can be fabricated at the desired location using paper sheets and copper film, without the need for lab facilities. This chapter reviews lightweight deployable origami antennas, providing theoretical and experimental results for a variety of examples, including a tetrahedron deployable origami antenna and a deployable quasi-Yagi monopole antenna utilizing origami magic spiral cubes.

This book discusses origami technology and its incorporation into wireless communication systems in the form of origami antennas.

Mutual coupling reduction or isolation enhancement in antenna arrays is an important area of research as it severely affects the performance of an antenna. In this paper, a new type of compact and highly isolated Multiple-Input-Multiple-Output (MIMO) antenna for ultra-wideband (UWB) applications is presented. The design consists of four radiators that are orthogonally positioned and confined to a compact 40 × 40 × 0.8 mm3 space. The final antenna design uses an inverted L shape partial ground to produce an acceptable reflection coefficient (S11 < −10 dB) in an entire UWB band (3.1–10.6) giga hertz (GHz). Moreover, the inter-element isolation has also been enhanced to >20 db for majority of the UWB band. The antenna was fabricated and tested with the vector network analyzer (VNA) and in an anechoic chamber for scattering parameters and radiation patterns. Furthermore, different MIMO diversity performance metrics are also measured to validate the proposed model. The simulation results and the experimental results from the constructed model agree quite well. The proposed antenna is compared with similar designs in recently published literature for various performance metrics. Because of its low envelope correlation coefficient (ECC < 0.1), high diversity gain (DG > 9.99 dB), peak gain of 4.6 dB, reduced channel capacity loss (CCL < 0.4 b/s/Hz), and average radiation efficiency of over 85%, the proposed MIMO antenna is ideally suited for practical UWB applications.

This paper presents a compact Multiple Input Multiple Output (MIMO) antenna with WLAN band notch for Ultra-Wideband (UWB) applications. The antenna is designed on 0.8 mm thick low-cost FR-4 substrate having a compact size of 22 mm x 30 mm. The proposed antenna comprises of two monopole patches on the top layer of substrate while having a shared ground on its bottom layer. The mutual coupling between adjacent patches has been reduced by using a novel stub with shared ground structure. The stub consists of complementary rectangular slots that disturb the surface current direction and thus result in reducing mutual coupling between two ports. A slot is etched in the radiating patch for WLAN band notch. The slot is used to suppress frequencies ranging from 5.1 to 5.9 GHz. The results show that the proposed antenna has a very good impedance bandwidth of |S11| < -10 dB within the frequency band from 3.1-14 GHz. A low mutual coupling of less than -23 dB is achieved within the entire UWB band. Furthermore, the antenna has a peak gain of 5.8 dB, low ECC < 0.002 and high Diversity Gain (DG > 9.98).

We propose a novel all-optical technique for the transmission of multiple channels over a single optical carrier by employing pulse position modulation (PPM). The proposed technique partly solves the issue of low spectral efficiency associated with the PPM transmission scheme. Furthermore, our proposed technique also improves the security of the FSO link against eavesdroppers, especially if they are located close to the receiver and are able to detect some part of the wide beamwidth optical signal. We have employed the Gamma–Gamma channel model to observe the performance of the FSO link for different lengths.

Artificial intelligence (AI)-based multispectral remote sensing has been the best supporting tool using limited resources to enhance the lithological mapping abilities with accuracy, supported by ground truthing through traditional mapping techniques. The availability of the dataset, choice of algorithm, cost, accuracy, computational time, data labeling, and terrain features are some crucial considerations that researchers continue to explore. In this research, support vector machine (SVM) and artificial neural network (ANN) were applied to the Sentinel-2 MSI dataset for classifying lithologies having subtle compositional differences in the Kohat Basin’s remote, inaccessible regions within Pakistan. First, we used principal component analysis (PCA), minimum noise fraction (MNF), and available maps for reliable data annotation for training SVM and (ANN) models for mapping ten classes (nine lithological units + water). The ANN and SVM results were compared with the previously conducted studies in the area and ground truth survey to evaluate their accuracy. SVM mapped ten classes with an overall accuracy (OA) of 95.78% and kappa coefficient of 0.95, compared to 95.73% and 0.95 by ANN classification. The SVM algorithm was more efficient concerning computational efficiency, accuracy, and ease due to available features within Google Earth Engine (GEE). Contrarily, ANN required time-consuming data transformation from GEE to Google Cloud before application in Google Colab.