Single-Conductor Planar Ladder Endfire Antenna

In this letter, a novel planar all-metal single-conductor planar ladder endfire antenna is introduced for the first time. The proposed antenna has the advantages of stable endfire radiation, broad bandwidth, low-cost, and easy assembly. By adopting the air-substrate feeding structure, the antenna achieves a moderate phase constant, leading to a stable endfire radiation pattern. Meanwhile, choosing a longer radiating element can produce a larger radiating aperture and thus attain a wider bandwidth. Moreover, by differentially feeding the radiating elements on both sides, the whole configuration has an integrated single-conductor design. Due to the novel single-conductor structure, the proposed antenna is low-cost and easy to assemble. Finally, the prototype is simulated, fabricated, and tested to validate its performance. The measured impedance bandwidth is 20% from 2.7 to 3.3 GHz. The measured 1 dB and 3 dB gain bandwidths are 13.3% and 28.3%, respectively.