Method of Suppressing the Side Lobe of a Tapered Short Leaky Wave Antenna

This letter demonstrates a method for suppressing the side lobe of a tapered short leaky wave antenna (LWA). The proposed LWA contains a tapered microstrip radiator with a shorting pin and two rectangular slots. This design of the two slots and the shorting pin can interfere with the current distribution of tapered LWAs to suppress the radiation of the side lobe. A matching stub is added along the feeding line to achieve impedance matching. According to the measured results, the proposed design improves the side lobe level (SLL) from 0 dB for the tapered short LWA (about 1.5lambda₀ at 4.5 GHz) to -6.13 dB for the proposed LWA at 6.4 GHz. The 7-dB impedance bandwidth is about 1.6 GHz, and the scanning range is about 43deg.