Reconfigurable Dual-/Triple-Band Circularly Polarized Dielectric Resonator Antenna

Abstract

In this letter, a probe-fed reconfigurable dual-/triple-band circularly polarized (CP) Spidron fractal dielectric resonator antenna (SFDRA) is proposed. Initially, a dual-band CP SFDRA is designed. An eigen-mode simulation of an isolated SFDR concludes that the quasi-TM11 delta and quasi-TM21 delta are excited in the lower band, whereas the quasi-TE12 delta mode is excited in the upper CP band. The modes of the lower CP band are separated by etching a T-shaped slot from the ground plane, thereby achieving overall triple-band circular polarization. In addition, the TSS being lambda(g)/2 in length at 2.64 GHz produces a band-notch function. CP band reconfigurability is attained by placing a diode D1 across the width of the TSS such that the ON-/OFF-state of the D1 radiates dual-/triple-band CP waves. The measurement results in the ON-[OFF]-state show the impedance bandwidths for vertical bar S-11 vertical bar < -10 dB of 57.60% (2.2-3.98 GHz) [14.44% (2.12-2.45) and 40.48% (2.64-3.98 GHz)] and the 3 dB axial-ratio bandwidths of 24% (2.31-2.94 GHz) and 6.82% (3.68-3.94 GHz) [6.34% (2.29-2.44 GHz), 6.65% (2.76-2.95) and 7.09% (3.67-3.94 GHz)] in an ascending order of the frequency. A reasonable match is observed between the simulated and experimental data.