Phase Progression of a Radiation Field From Circular and Square Active Regions

• Published in: IEEE access 2021, Vol.9, p.14710-14724
• Main Authors: Nakano, Hisamatsu, Abe, Tomoki, Yamauchi, Junji
• Format: Article
• Language: English
• Subjects: Active region; Antenna arrays; Antenna radiation patterns; Antennas; Azimuth; Conductors; metaloop; natural loop; Perturbation methods; phase progression; radiation field; Spirals; Wavelengths
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2021.3051949

The radiation generated by the current in an active region (ACT-R), specified by propagation phase constant \beta , is investigated with special interest in its phase progression (PhasProg). The ACT-R is modeled by circular and square loops, and classified into two types: a right-handed ACT-R with positive \beta and a left-handed ACT-R with negative \beta . Firstly, a circular ACT-R of a length of n guided wavelengths is formulated. It is found that, at any depression angle \theta , the PhasProg with respect to azimuth angle \phi is downward-sloping for the right-handed ACT-R and upward-sloping for the left-handed ACT-R. These PhasProgs have a perfectly linear change of 360n degrees ( n =1 , 2) with respect to azimuth angle \phi . Secondly, a square ACT-R of a length of n guided wavelengths is formulated. When k_{0}/\vert \beta \vert =1 with k_{0} being free-space phase constant, the PhasProg is found to be downward-sloping for the right-handed ACT-R and upward-sloping for the left-handed ACT-R, with a quasi-linear change of 360n degrees ( n =1 , 2) with respect to azimuth angle \phi . Thirdly, the formulated numerical expressions are compared with simulated results obtained using natural and metaloop antennas, and reasonable agreement between these is observed. Fourthly, a comment is made on a singular phenomenon of the PhasProg for n =2