Low-Profile Millimeter-Wave Broadband Metasurface Antenna With Four Resonances

A millimeter-wave (mmWave) broadband metasurface antenna with low profile is proposed. The radiator composed of four groups of coplanar patches with different dimensions has four adjacent broadside characteristic modes. Coaxial probe feeding is selected carefully to excite the four modes to broaden impedance bandwidth. Dual slots are etched on the patch fed by the coaxial probe to reduce H-plane cross-polarization levels. Characteristic mode analysis (CMA) and input impedance analysis are performed to characterize its resonance behaviors. The proposed antenna with dimension of 1.03 × 1.03 × 0.023 λ
₀
³
(λ
₀
is wavelength at 28 GHz in free space) realizes 16% (26.1 GHz-30.7 GHz) impedance bandwidth for |S
₁₁
| ≤ -10 dB. Realized peak gain is up to 10.1 dBi and 3 dB gain bandwidth is 22% (24.4 GHz-30.5 GHz). H-plane cross-polarization levels are less than -16 dB.