Circularly Polarized Phased Array Based On Reconfigurable Plasma Material Without Phasing Network In Near/far Field Regions

Abstract

This paper presents a new type of phased array antenna (PAA) that uses plasma material to achieve circular polarization characteristics. The plasma controls the phase shift of individual elements without the need for conventional phase shifters feeding network. The PAA is made up of 64 plasma dipole elements arranged into $4\times 4$ sub-arrays, each consisting of $2\times 2$ sequentially rotated plasma dipole elements with different plasma ionization frequencies. The PAA is designed to radiate either right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP). Two different sub-array arrangements are designed with plasma frequencies distribution of $(\omega_{\mathrm{p}1},\omega_{\mathrm{p}2},\omega_{\mathrm{p}1},\omega_{\mathrm{p}2})$ for arrangement (I), and $(\omega_{\mathrm{p}1},\omega_{\mathrm{p}2},\omega_{\mathrm{p}^3},\omega_{\mathrm{p}4})$ for arrangement (II). The frequency for minimum axialratio is controlled by selecting $\omega_{\mathrm{p}1}$, and $\omega_{\mathrm{p}2}$. PAA is designed to radiate right-hand circular polarization (RHCP) with peak gain of 20.9 dBi, and the 3-dB bandwidth $(\text{AR} < 3\text{dB})$ is 200 MHz. In arrangement (II), PAA radiates left-hand circular polarization (LHCP) with peak gain 19.1 dBi and AR bandwidth of 440 MHz. The NF-focused array focuses the field on a spot width of 4.4 cm compared to 6.6 cm for the non-focused array. A near-field focused PAA is also designed using one of the sub-array arrangements (I). This array focuses the field on a narrower spot compared to the non-focused array.