Textbook in PDF format Mode-Inspired Wideband and Multiband Planar Antennas delivers a complete engineering methodology for designing wideband and multiband planar antennas with a focus on mode-inspired theory. Understand the evolution of planar antenna technologies and the critical bandwidth types, including Impedance, Isolation, Gain, and Pattern. This book offers the practical and theoretical foundations of characteristic and cavity mode analysis to enable the production of low-profile, single-layer planar antennas that are both compact and high-performance. Dive deep into the exact methodologies and techniques that form the theoretical basis for bandwidth control across all domains. Gain detailed knowledge of essential strategies like harmonic suppression, even/odd mode control, and coupling interface design for improving port isolation in MIMO and full-duplex systems. Also cover the implementation of high and stable gain approaches for directional and GPS-based systems, as well as advanced radiation control for half-power beamwidth (HPBW), reducing sidelobes and cross-polarization, and designing scanning-beam strategies. Further consideration is given to applications for biomedical and implantable systems in space-constrained or high-demand environments. This resource is an essential tool for RF engineers, antenna designers, academic researchers, graduate students, and wireless communications professionals working with advanced planar antennas. Get solutions to key problems such as achieving high-performance in compact and low-profile designs, improving port isolation in MIMO systems, and optimizing gain and radiation patterns for a variety of challenging applications, from mobile antennas to conformal antennas and GPS systems. Over the past three decades, planar antennas—such as microstrip patch antennas, slot antennas, and printed dipole antennas—have gained popularity due to their inherent advantages, including low profile, compact size, and ease of fabrication. As a result, they have been widely used in applications like cellular communication, satellite communication, and radar systems. However, as modern communication systems evolve to support multifunctionality, multiuser connectivity, and enhanced performance under constrained conditions, traditional planar antennas face limitations because they typically operate using only a single fundamental mode. To address this challenge, the concept of multimode resonance (MMR), originally developed for filters, has been adapted for antennas by research teams worldwide. This approach enables more efficient use and control of both fundamental and higher-order modes, improving impedance and radiation characteristics, and significantly expanding the performance potential of planar antennas. Compared to other methods, the MMR approach in planar antennas offers four major advantages. First, it enables the use of multiple resonant modes within a single radiator, reducing the number of required antenna elements and lowering the overall antenna thickness. Second, the MMR methodology introduces a novel analytical framework that clarifies the underlying physical principles, thereby improving design efficiency. Third, this approach transforms traditionally unusable higher-order modes into beneficial modes with enhanced performance. Fourth, MMR techniques overcome the performance limitations of conventional planar antennas, often yielding unexpected improvements in radiation characteristics. Preface Introduction Multimode Resonance-Inspired Theory of Wideband and Multiband Planar Antennas Multimode Resonance-Inspired Planar Antennas with Impedance Bandwidth Improvement Multimode Resonance-Inspired Planar Antennas wit