Miniaturized Slow-Wave SIW-Based Circularly Polarized CRLH Leaky Wave Antenna Array Supporting Wide Angle Beam Scanning for Radar Applications

This paper presents a multi-layered composite right-left-handed (CRLH) slow-wave substrate integrated waveguide (SW-SIW) circularly polarized (CP) leaky-wave antenna (LWA) having wide impedance bandwidth (measured: 14.6–18.25 GHz). The CRLH unit cell consists of three radiating slots on top metallic layer, arranged in a crown-shaped fashion, to achieve wideband circular polarization.The bottom ground plane of the standard SIW is connected to the SW structure of the LWA that consists of internal metalized blind vias. Due to the SW effect, a 33% reduction in lateral dimension is achieved, compared to a conventional SIW having the same cut-off frequency. At the same time, the phase velocity is also reduced leading to a reduction in longitudinal dimensions. The dimensions of the antenna are relatively small, with a size of 3.2 × 0.4x.07 λ³. The operating mechanism of the LWA having symmetrical and continuous backward-to-forward scanning range from −64 ° to 64 ° (128 °) is explained by an equivalent circuit model. The measured CP bandwidth (14.6–18.43 GHz) of the LWA completely overlaps the 10-dB return loss bandwidth. The compact dimension, wide symmetric beam scanning, completely overlapped CP, and return loss bandwidths are the major advantages of the proposed antenna.The LWA exhibits stable gain with a peak value of 11.3 dBic (gain variation: from 9.7 to 11.3 dB). The radiation efficiency of the LWA is above 85% within the impedance bandwidth.