Abstract
A novel design for a beam-switching antenna using active cylindrical slot frequency selective surface (ACSFSS) is presented. The antenna system is composed of an omnidirectional monopole antenna and the ACSFSS, which employs a new technique of switching slot arrays. The ACSFSS is made up of 12 columns with 8 slots each, dividing the cylinder by 30 $^{\circ}$ . To steer the beam of the antenna the diodes are set off and on, so that the radiation pattern of the antenna is determined by the number of off state columns. To estimate the general dimension of the cylindrical FSS, an equivalent metallic reflector is introduced and optimized, and then parametric studies for the unit cell dimensions are discussed. The fabricated prototype works within the WLAN band, centered around 2.45 GHz, and can agilely select either a narrow-beam or wide-beam operating mode. Simulation and measurements confirm the operation of the ACSFSS antenna, with good matching and gain observed. In particular, the narrow-beam mode $-$ 3 dB beamwidth is 47 $^{\circ}$ which offers enhanced angular resolution compared with other reported beam-sweeping work.
Highlights
A S A COMMON technology nowadays, most wireless local area networks (WLAN) use the same frequency band in the narrow range lying between 2.4–2.5 GHz
A cylindrical active frequency selective surfaces (FSS) antenna using slot unit cells is proposed for beam-switching application
A model based on unslotted reflectors can be used effectively to optimize the radius of the cylinder to obtain the radiation characteristics of the active cylindrical slot frequency selective surface (ACSFSS) antenna
Summary
A S A COMMON technology nowadays, most wireless local area networks (WLAN) use the same frequency band in the narrow range lying between 2.4–2.5 GHz. By switching the diodes states, sectors of the ACPFSS cylinder can be made either transparent or opaque in the operating frequency band, so that the antenna beam can be steered in required patterns and directions. Since the basic unit cell of the FSS in these designs employed discontinuous conducting patches connected by pin diodes, the FSS could not provide a completely transparent level for the incident waves at the desired frequency when diodes were activated. As a result, this considerably degrades the performance of the radiation pattern, as mentioned in [11].
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