Design and Development of Band-Notched UWB Microstrip Patch Antenna using Nature Inspired Optimization Algorithms

Abstract

Wireless communication has experienced remarkable and rapid growth in recent times, driven by advancements in wireless technology. This progress has led to continuous reductions in the size of modern wireless devices. These devices now provide a wide range of applications within wireless personal area networks (WPAN). WPAN applications include home entertainment purposes such as digital video discs (DVDs) and LCD High-Definition TVs (HDTVs), academic purposes like wireless USB and wireless printer/scanners, as well as multimedia applications like video conferencing and online gaming. WPAN technology provides the convenience of interconnecting various devices in both home and office settings without the need for physical wires. Achieving fast data rates is a critical priority for such devices, and this can be accomplished by expanding the bandwidth. Ultra-wideband (UWB) technology presents the most promising solution to achieve large bandwidth while consuming minimal power, primarily due to its extensive frequency spectrum ranging from 3.1 GHz to 10.6 GHz. Therefore, UWB antennas play an important role in establishing a wireless link for the WPAN appliances by providing a large signal bandwidth. However, designing a UWB antenna is a challenging task as it must meet the requirements for providing wideband performance in accordance with the Federal Communications Commission (FCC) norms. Some specific UWB systems suffer from narrow-band signal interference of other unlicensed ISM band wireless communication devices, such as WI-MAX, ARN, WLAN, and ITU-8 X-band of satellite downlink frequency channel. In order to avoid this interference, UWB antennas require in-built filter properties by incorporating different types of slots, strips, or slits into the radiating patch. To achieve this objective, the research proposes three different designs of UWB antennas with dual band-notch (DBN), triple band-notch (TBN), and quadruple band-notched (QBN) characteristics. These designs exhibit sharp band-rejection features. The antennas are constructed using a direct geometrical method to determine the dimensions of the band-notch elements, which serve as notch resonators. However, this process presents challenges and is time-consuming as it involves a trial-and-error approach to adjust the dimensions of these elements. To address this challenge effectively, global optimization techniques are required. Nature-inspired algorithms are one of the most important types of global optimization methods, which have been used to solve problems of various real-world applications. These sophisticated algorithms draw inspiration from natural processes observed in various species and have proven efficient in determining the optimal solutions for a wide range of engineering problems, including electromagnetic antenna design. These algorithms provide more effective solutions compared to the traditional hit-and-trial methods, leading to improved antenna design and performance. Therefore, the research proposes three novel optimization techniques based on the recently introduced naked mole-rat (NMR) algorithm. The first technique, called Levy mutated naked mole-rat algorithm (LNMRA), aims to optimize the structure of a dual band-notch UWB (DBN-UWB) antenna. The second technique uses a hybrid differential evolution and naked mole-rat algorithm (HDN) to optimize a triple band-notch UWB (TBN-UWB) antenna. For the third technique, a hybrid binary version of grey wolf optimizer and naked mole-rat (HbGNMR) is proposed to design a planar fragment-type binary UWB (P-UWBFT) antenna. All of these techniques are employed for single-objective optimization purposes. Furthermore, single-objective optimization techniques may not be the most suitable approach to achieve optimal antenna designs, especially for complex design structures. Since the antenna design is inherently a multi-objective problem, it involves several contrary objectives that need to be addressed simultaneously. These objectives include balancing size reduction with gain maximization, size reduction with operating frequency minimization, maximizing both gain and beamwidth, and minimizing signal reflection (|S11|) by focusing on gain maximization. Thus, the research work proposes two multi-objective optimization algorithms. First is the multi-objective naked mole-rat (MONMR) algorithm to address the design challenges of basic UWB (B-UWB) and TBN-UWB antennas. Secondly, a multi-objective multi-hybrid naked mole-rat (moIGDN) algorithm to optimize the B-UWB and DBN-UWB printed monopole antennas. This thesis focuses on developing compact-sized UWB antennas with band-notched characteristics suitable for WPAN applications. The design process utilizes an analytical model to achieve the desired frequency response without relying on specific mathematical values. These antennas are designed and analyzed using an electromagnetic (EM) simulator. For prototype fabrication, an FR-4 substrate with a thickness of 1.6 mm is used, and the antennas are fabricated through a wet etching and photo-lithography process. The fabricated antennae are then measured on RF experimental testbed using a vector network analyzer (VNA) model no. E5063A. Various parameters of the proposed antennas, such as reflection coefficient (ᴦ), voltage standing wave ratio (VSWR), and input impedance (Z), are carefully observed. Additionally, radiation measurement analysis are performed, including 2D and 3D radiation patterns, antenna gain, and current distribution, achieved by placing the antenna in an anechoic chamber. The measured results show good agreement with the simulated results, with only minor variations observed. The designed antennas have been demonstrated to be good candidates for UWB applications.