Dual/circular polarization beam shaping of time-modulated plasma-based magneto-electric dipole antenna arrays

This paper introduces a plasma based circularly polarized (CP) magneto-electric (ME) dipole antenna as a building element of time-modulated array (TMA). The single plasma ME-dipole element introduces impedance matching bandwidth of 2.75 GHz and high gain of 9.1 dBi. The element maintains right-hand circular polarization  (RHCP) characteristics of 320 MHz with broadside wide beam radiation. A linear arrangement of 16-element spaced by 0.65λ and connected with 16 RF-switches with periodic switching frequency of 100 MHz is investigated. The switching time-sequences are estimated using PSO through minimizing the error between the desired and calculated radiation patterns. Different shapes of beams are designed using controlled on-time switching sequences like pencil, flat-top, sum, and difference patterns. The side-lobe levels (SLL) are controlled below − 25 dB for the designed beams. Planner arrangement of 8 × 8 plasma ME-dipole elements are investigated. Pencil-pencil or pencil-flat top beams are designed at the fundamental and first harmonic frequencies. A sequential arrangement of 4- and 16- elements are designed to improve the circular polarization radiation characteristics. By controlling the switching time duration and delay between array elements, two modes of electric fields with orthogonal phase and equal amplitudes are generated. Circular polarization bandwidth of 1.3 GHz is obtained with high gain of 15.3 dBi and 21.9 dBi for the 4-element array and 16-element array, respectively.