Design of pattern-reconfigurable circularly polarized unidirectional antenna based on quasi-radiator for ISM applications

Abstract

A pattern-reconfigurable circularly polarized antenna for 2.45 GHz industrial, scientific, and medical (ISM) band applications is designed in this work. The proposed antenna consists of a slotted-stepped monopole connected to a rectangular ground plane via a shorting side-stub. This converts the omnidirectional radiation pattern of the antenna into stable unidirectional radiation. To dynamically steer the realized pattern, two switchable RF PIN diodes are jointly incorporated into the side-stubs to achieve symmetrical radiations in specific operating modes. In this way, the radiation patterns can be simultaneously tuned in the ±y directions by the simple switching of the PIN diodes ON and OFF. The fabricated prototype achieves an S11 smaller than -10dB within the 3dB axial ratio (AR) bandwidth with stable far-field patterns. The antenna maintains a low-profile and compact size of 0.055λ02 which makes it suitable for body-centric wireless communication (BWC) and personal wireless area networks.

Keywords

• Pattern-reconfigurable
• PIN diode
• Circular polarization
• Unidirectional radiation