Search

A new adaptive frequency selective surface (AFSS) has been presented for electromagnetic (EM) shielding applications. Passive EM shields lack reconfigurability which severely limits their application. Moreover, active EM shields involving PIN diodes and other active elements consume power all the time. This paper incorporates a novel adaptive approach with frequency selective surface (FSS) to create a smart environment. The unit cell of the designed FSS has the shape of an octagon loop; each loop includes a pin diode at 180° intervals. An envelope detector has been used to trigger the microcontroller whenever an incident RF signal has been detected. The PIN diodes are switched ON or OFF automatically based on the requirements using a microcontroller to save power. When the PIN diodes are OFF, the FSS is in the shielding mode and when they are ON it is in the transmission mode. A prototype has been built for measurements. A good agreement between theory and experiment has been observed. The proposed AFSS can also be programmed as a time-based event and remote-controlled for on-demand EM wave shielding applications.

A wideband bandstop frequency selective surface (FSS) for electromagnetic interference (EMI) reduction applications is presented for the S-, C-, and X-bands. The proposed FSS is made of convoluted square and circular loop elements, which are employed on the opposite surfaces of the RO3010 substrate. The overall dimensions of the FSS are reduced to 0.15λ at the center frequency compared with the conventional loop elements with an overall decrease in the size of more than 90% at the center frequency. It has a bandwidth of 9 GHz to reduce the harmful effects on the human body due to EMI caused by radio transceivers. It can also be employed as a sub-reflector to enhance the gain and the bandwidth of the antennas. Furthermore, it has many advantages in comparison to the designs presented in the latest research. For example, it has a low profile, the fractional bandwidth is enhanced up to 120%, and it ensures better angular stability for transverse electric (TE) as well as transverse magnetic (TM) polarized waves. Moreover, an average signal attenuation of more than 30.60 and 19.5 dB is ensured in the entire band for TE and TM modes, respectively. The simulation results are obtained using a high-frequency structure simulator (HFSS) and validated through the experimental results.