A Miniaturized Dual-Band Dual-Beam Filtering Patch Antenna With Orthogonal Beam Pointing

A miniaturized dual-band dual-beam filtering patch antenna with orthogonal beam pointing is proposed. By using a cross-shaped feedline with two pairs of orthogonal common-mode (CM) currents, TM02 and TM20 modes are excited with suppression of adjacent TM10 and TM12 modes, and radiation null 1 (RN1) is introduced in both polarizations. Due to far-field nulls of orthogonal dual-beam patterns, intrinsic radiation null 1 (RN <tex-math notation="LaTeX">ᵢ₁ </tex-math> ) and RN <tex-math notation="LaTeX">ᵢ₂ </tex-math> are generated. With miniaturization, by etching periodic short slots, RN <tex-math notation="LaTeX">ᵢ₃ </tex-math> related to the high-order harmonic can be used, its frequency can be significantly controlled, and the radiation pattern is reshaped to effectively improve the rejection at RN <tex-math notation="LaTeX">ᵢ₃ </tex-math> in <tex-math notation="LaTeX">x </tex-math> -polarization. To ensure high selectivity at each sideband while remaining compact, nested two quasi-circular loops (QCLs) and a cross-shaped metal strip (CSMS) are employed to create RN2–RN4 in both polarizations. Thus, a total of eleven RNs are yielded, aching high selectivity and deep stopband rejection. With a small size of <tex-math notation="LaTeX">0.40λ ₀ × 0.44λ ₀ × 0.028λ ₀ </tex-math> , a prototype is fabricated and tested. Measured results show that dual beams in 5.3–5.53 GHz point toward the <tex-math notation="LaTeX">x </tex-math> -axis direction, while dual beams in 6.34–6.66 GHz point toward the <tex-math notation="LaTeX">y </tex-math> -axis direction, satisfying the requirements of point-to-multipoint scenarios providing different wireless services in orthogonal orientations.