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Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account.The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations.
The realized measured peak gain ranges between 1.9 d Bi and 6.3 d Bi, while the cross-polarization levels are of about 15 d B and 20 d B in the Figure 1: A monopolar patch antenna with a circular patch, circular ground plane, and two coupled metal rings . Dark gray monopole and light gray dielectric substrate., has been presented in .
Two zig-zag slots and two rectangular notches have been inserted in the patch for achieving a wider impedance bandwidth with higher return loss levels.
In Section 3, the characteristics of monopole antennas over metal plates are discussed.
In Sections 4, 5, and 6, the performances of planar printed monopole, wide-slot, and dipole antennas for wideband and UWB applications are illustrated.
As a first structure, a wideband patch antenna having a radiation pattern similar to that of a monopole and consisting of two metal rings coupled to a circular patch radiator, presented in  is illustrated.
The antenna is printed on a circular grounded dielectric substrate (Di Clad 527), with relative permittivity , while a coaxial probe, located at the center of the circular patch, is used to excite the antenna (see Figure 1).
In fact, the rapid growth of mobile systems toward the fifth-generation (5G systems) requires multiband, wideband, and UWB antennas suitable to cover mobile and wireless services and to reduce the system complexity, the overall device dimensions, and costs.
Many efforts are underway to identify new antenna geometries suitable to satisfy the challenging requirements of the modern wireless communication systems [1–4].
To this end, in this paper a comprehensive review of the scientific literature of the last decade concerning these aspects is taken into account with the aim to provide researchers and designers with a valuable support tool to the antenna design.
Particular emphasis is given to geometries, radiation mechanisms, broadbanding methods, materials, and prediction numerical tools adopted to the analysis and design of these important classes of antennas. In Section 2 the features of some wideband microstrip antennas are presented.