A dual-beam frequency scann ing microstrip antenna is proposed in this letter. The wellknown characteristic of the conventional leaky wave antenna is the beam scanning with operating frequency variation. Here, four slots are applied on the ground plane of the conventional leaky wave antenna structure to obtain the dual-beam frequency scanning characteristic. According the results, it shows that this work with relatively simple structure radiating not only in upper half-plane, but also in lower half-plane. The upper half-plane main lobe scans from 356˚ (-4˚) to 24˚ (scanning region is 28˚). Meanwhile, the lower half-plane main lobe scans form 190˚ (-170˚) to 161˚ (scanning region is 29˚). The 7-dB return loss bandwidth is 600 MHz from 3.4 GHz to 4 GHz. In addition, the measured average antenna gain is about 5.3 dBi in the operating frequency.
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