In-line series-feed collinear slot array fed by a coplanar waveguide

The in-line series-feed collinear slot array antenna fed by a coplanar waveguide is investigated thoroughly. Radiating elements are placed end-to-end along the shunt slotline pair transverse to the feedline. This simple linear array structure increases the antenna gain and shapes the H-plane pattern. The shunt slotine pair can be terminated by either short or open circuit. The Short ends, the slotline circular open stubs, and the directly-truncated open ends are used as terminations. Design guidelines for the three cases are given separately. A reflector-backed arrangement, with which the proposed antennas would be able to radiate unidirectional patterns, is also discussed. Experimental results, which agree well with the simulated ones, verify the performances of the proposed antennas.