A new adjustable frequency waveguide circularly polarized antenna based on the solid-state plasma

Abstract

In this paper, a circularly polarized antenna is realized based on the solid-state plasma (SSP), and its working frequency band can be adjusted slightly by simulating the different SSP branches. The proposed antenna is similar to other common coplanar waveguide antennas, but its metal radiation patch and reflective ground are in different planes, which are located at both sides of the dielectric layer. The dielectric layer is made of FR4, and the metal radiation patch and reflective ground are the copper. There are two adjustable branches composed of SSP, which can be excited to tailor its operating frequency. The simulated results show that the proposed antenna can operate at two main communication bands, which are WLAN (2.4–2.4835 GHz) and WiMAX (3.3 GHz), when the different SSP branches are excited. To verify the reliability of the design, two equivalent prototypes have been fabricated and measured. The measured results are probably consistent with simulated results within a reasonable error range. The measured results show that when the left SPP branch is excited (state A), the 10-dB return loss bandwidth is 57.1% (2–3.6 GHz), and the 3-dB axial ratio (AR) bandwidth is 31.1% (1.9–2.6 GHz) containing WLAN. When the right SPP branch is excited (state B), the 10-dB return loss bandwidth is 57.1% (2–3.6 GHz), and the 3-dB AR bandwidth is 31.6% (2.4–3.3 GHz) containing WiMAX. In addition, the better performance of such an antenna can be obtained within a certain angle region.