This paper reports on the study of a new antenna as well as a five-element array prototype developed for communications in K-band and suitable for low temperature co-fired ceramic technology. The radiating element is an open waveguide realized in laminated technology. A special coaxial-to-waveguide transition has also been designed as feed port for measuring the prototypes. The element exhibits a 1 GHz bandwidth centered at 20.7 GHz and a 2.7 dBi gain. In an array configuration, mutual coupling between the elements is lower than -18 dB across the bandwidth. The simulated boresight radiation pattern of a five-element array is stable over the bandwidth and the gain reaches 9.2 dBi at 20.7 GHz. The measurements of the radiation pattern for a 20-degree scan angle, as well as the simulation, demonstrate the scanning capability of this array.