Two novel short tapered leaky wave antenna (LWA) designs with a complementary split ring resonator (CSRR) structure are proposed in this paper. The CSRR structure is positioned at 1/4 lambda(g) away from the open-end edge of the LWA. For one of the antenna designs, the CSRR is placed at the ground plane; for the other one, the CSRR is placed on the antenna plane. The reflected wave caused by the open-end edge of the LWA is cancelled by the reflected wave caused by the CSRR, thus, the back lobe can be effectively suppressed. The length of these two short tapered LWAs with CSRR design is only 1.2 lambda(g) at 4.3 GHz. According to the measurement results, the impedance bandwidth is 650 MHz for 7 dB return loss, which covers the range from 4.3 GHz to 4.95 GHz. The back lobe can be suppressed effectively about more than 12 dB at the whole operating frequency band. The scanning range of the main beam is about 34 degrees, which cover the scanning angle from 10 degrees to 44 degrees.
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