Backward-to-Forward Scanning Periodic Nonuniform Leaky-Wave Antenna for Reflected Sidelobe Suppression

A backward-to-forward continuous beam scanning periodic leaky-wave antenna (PLWA) with eliminated reflected sidelobe in both forward and backward quadrant is presented in this letter. The proposed antenna consists of ten nonuniform unit cells (UCs) composed of orthogonally bending transmission lines. The open stopband is suppressed by optimizing the impedance matching through adjusting the widths of two transversal lines in UC. Gradient change in the geometries of the UCs along the direction of propagation is applied to achieve reflected sidelobe suppression. A prototype of the antenna is simulated, fabricated, and measured. The measured results show that the main beam scans continuously from −51° to +60° in the frequency band of 3.7–6.5 GHz. The proposed antenna features a low reflected sidelobe level in both forward quadrant and backward quadrant, and achieves a maximum reduction of 7.9 dB at 6.5 GHz compared to the conventional uniform PLWA.