A tapered CPW fed leaky-wave antenna based on substrate integrated waveguide with reduced side-lobe level

A novel method for confining the undesired radiation of the feed transition of a low-profile leaky-wave antenna (LWA) is demonstrated in this paper. The proposed design method uses novel tapered CPW transitions resulting in variation of the parasitic capacitance and electrical length of the feed. This leads to the reduction of the side-lobe level (SLL), which is dictated by the feed and the slotted sections of the antenna. The undesired radiation from the feed becomes crucial in the low-profile antenna in which the surface-mounted connector along feed transition is the only practical feeding mechanism. The key novelty of the proposed approach is the reduction of SLL by exclusively modifying the feed structure rather than the slotted radiation section. To validate the proposed approach, a modified compact feeding mechanism for LWA is designed. The antenna is realized based on the substrate integrated waveguide (SIW). The antenna's length, width, and height are 110 mm, 31 mm, and 0.5 mm, respectively. The operating frequency band was chosen as 26 to 30 GHz, covering an allocated 5G band. The measured peak realized gain and SLL are 6.1 dBi and - 11.4 dB, respectively. An improvement of 5.7 dB in SLL compared to the conventional LWA was observed. The simple fabrication process and efficiency of the proposed method make it a viable approach for reducing the SLL of the low-profile antennas. Compactness, low SLL, and proper gain of the reported antenna make it a suitable candidate for 5G vehicle to everything (V2X) communications and mm-wave navigation systems.