A Compact Frequency Scanning Planar Array Using Characteristic Mode Analysis

Abstract

In this letter, a compact planar array with frequency scanning characteristics is proposed. Based on the characteristic mode analysis (CMA), we found that there distribute four modes with distinctive radiation patterns and phase characteristics. And combining them in pairs would generate scanning beams within a narrow band. In addition, CMA offers us useful guidelines on enhancing the gain and suppressing the sidelobes. A prototype was fabricated and measured. Under the excitation of a single port, namely <inline-formula><tex-math notation= LaTeX >$P_{1}$</tex-math></inline-formula>, the scanning range was from <inline-formula><tex-math notation= LaTeX >$14^{\\circ }$</tex-math></inline-formula> to <inline-formula><tex-math notation= LaTeX >$51^{\\circ }$</tex-math></inline-formula> with sidelobe level (SLL) lower than −20\xa0dB. As switching the port from <inline-formula><tex-math notation= LaTeX >$P_{1}$</tex-math></inline-formula> to its symmetrical port, <inline-formula><tex-math notation= LaTeX >$P_{2}$</tex-math></inline-formula>, the scanning scope in the <italic>E</italic>-plane would be extended to the mirrored space from <inline-formula><tex-math notation= LaTeX >$-14^{\\circ }$</tex-math></inline-formula> to <inline-formula><tex-math notation= LaTeX >$-51^{\\circ }$</tex-math></inline-formula>.