Reconfigurability in an antenna system is a desired characteristic that has been the focus of much research in recent years. In this work, ohmic contact cantilever RF-MEMS switches are integrated with self-similar planar antennas to provide a reconfigurable antenna system that radiates similar patterns over a wide range of frequencies. The different issues encountered during the integration of the MEMS switches and the overall system design procedure are described herein. The final model radiates at three widely separated frequencies with very similar radiation patterns. The proposed concept can be extended to reconfigurable linear antenna arrays or to more complex antenna structures with large improvements in antenna performance.

A MEMS reconfigurable ultra-wideband (UWB) antenna that rejects on-demand all WLAN signals in the entire 5.15 to 5.825 GHz range (675 MHz bandwidth) is presented. The antenna design, miniaturization procedure, and monolithic integration with the MEMS and biasing network on SiO₂ Quartz substrate are described. The integration challenges are addressed and the work is presented in a way that is useful for antenna engineers. A method to vary the rejection bandwidth is also provided. The fabricated prototype is conformal and single-sided. The antenna is measured using a custom-built platform at a university laboratory. Results indicate a successful integration and minimal interference of the MEMS and biasing circuitry with the antenna, paving the road for more integrated reconfigurable antennas on SiO₂ using MEMS technology. Such antennas can improve UWB, WLAN and cognitive radio communication links.

The quality factor, Q, for a number of configurations of a microstrip antenna is evaluated using exact and approximate quality-factor formulas found in the literature. A number of slits parallel to the radiating edges are used to miniaturize the microstrip antenna's size. The microstrip antenna in use is considered to be electrically small according to Wheeler's electrically small antenna definition. The Q for each configuration is numerically evaluated using the given expressions, for simulated and measured data, and is compared to the Chu lower bound. There is good agreement between the results, while the Q lower fundamental limitation is not violated. Despite the size reduction, satisfying radiation efficiency is achieved, and the radiation pattern remains unchanged.

A two-branch diversity antenna using a simple printed dual band double-T monopole and operating at 2.4 and 5.2 GHz in the ISM band is presented. A prototype of the proposed antenna has been constructed and tested. The measured results are in good agreement with the computed ones from simulation, while the antenna has favourable characteristics such as reduced size and extended bandwidth.

The Internet of Things (IoT) envisions the interconnection of all electronic devices, ushering in a new technological era. IoT and 5G technology are linked, complementing each other in a manner that significantly enhances their impact. As sensors become increasingly embedded in our daily lives, they transform everyday objects into “smart” devices. This synergy between IoT sensor networks and 5G creates a dynamic ecosystem where the infrastructure provided by 5G’s high-speed, low-latency communication enables IoT devices to function more efficiently and effectively, paving the way for innovative applications and services that enhance our awareness and interactions with the world. Moreover, application-oriented and multifunctional antennas need to be developed to meet these high demands. In this review, a comprehensive analysis of IoT antennas is conducted based on their application characteristics. It is important to note that, to the best of our knowledge, this is the first time that this categorization has been performed in the literature. Indeed, comparing IoT antennas across different applications without considering their specific operational contexts is not practical. This review focuses on four primary operational fields: smart homes, smart cities, and biomedical and implantable devices.