One of the successful choices that satisfy the requirements of IoT applications is the reconfigurable antennas 6, 7, 8. For these reasons, a careful design of an antenna that can satisfy the requirements of the next IoT technologies is a vital necessity 4. The antenna is characterized by its large size with respect to other components, and it will be impractical to design an antenna for each frequency band on the same platform. This in turn has led to the possibility of exploiting a single wireless device in more than one application, and then more than one frequency band has to be utilized. By the way, the tremendous speed of progress in wireless communications techniques has led to an urgent necessity to design a high-speed system with efficient spectrum utilization. The IoT technology put big challenges on the working communications systems as a huge amount of data is required to be transferred between the wireless nodes connected to the network 5. The IoT merges the human and his surrounding wireless devices and sensors in a single network in real-time 1, 2, 3, 4. Recently, IoT has become an evolutional technology that aims to ease communication between human beings and their surrounding environment.
The behavior of the flexible antenna has been evaluated in both the flat and bent states, and stable performance has been observed in both cases. A maximum gain of 6.5 dBi, 7.52 dBi, and 7.91 dBi has been achieved at the three frequency bands respectively. The FSS operates efficiently from 2 to 4.5 GHz and has improved the gain of the antenna. To improve the gain of the antenna, a simple FSS surface is designed to be placed under the antenna at a distance of 15 mm. Three frequency modes of operation have been obtained the 2.4 GHz frequency band with the right-hand arm is fully truncated, the 3.5 GHz frequency band with the two arms is completely maintained, and the 4 GHz frequency band with the right-hand arm is partially truncated.
The length of the right-hand arm of the antenna is used to achieve frequency reconfiguration by using PIN diodes. This antenna is a coplanar waveguide (CPW)-fed monopole with two balanced arms printed on a thin ROGERS 3003 flexible substrate. The proposed antenna operates at three of the IoT frequency bands. This paper proposes a flexible, frequency-reconfigurable monopole antenna design with frequency selective surface (FSS) for Internet of Things (IoT) applications.
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