Frequency Scanning Single-Ridge Serpentine Dual-Slot-Waveguide Array Antenna

This paper presents a novel one-dimensional (1D) frequency scanning dual-slot-waveguide array antenna with versatile advantages such as large scan volume, high frequency sensitivity, low cross-polarization and low sidelobe. Electromagnetic waves radiate through the leaky-wave dual slots, machined on the side chambers of the single-ridge serpentine waveguide. By properly designing the serpentine waveguide, which plays the role of delay line, such 1D frequency scanning array antenna can achieve 39° scanning over a frequency range from 9.7 GHz to 10.3 GHz, and high frequency sensitivity of 65°/GHz. The dual slots with all the adjacent monomers inclined in same direction are designed to acquire low cross-polarization and avoid high-order mode radiation. The cross-polarization is 45 dB lower than the corresponding co-polarization over the whole working band. Taylor aperture distribution is employed to achieve a low sidelobe (-21 dB). The nonresonance VSWR is below 1.2, and meanwhile the resonance VSWR remains a low level, around 2.5. Furthermore, our proposed 1D array as a building block can compose a novel 2D electric scanning array, with frequency scanning in one dimension and phase scanning in the orthogonal dimension. A 2D array consisting of three waveguide elements is simulated to predict the phase scanning performance, and the results indicate that a 120° scanning performance can be obtained. At last, a 1D serpentine dual-slot-waveguide array antenna is fabricated, whose measurements show good agreement with simulations.