Low-cost antenna elements for reducing grating lobes

Antenna arrays based on grating lobe reduction were introduced last years [1-2]. One of the main advantages of this kind of antenna arrays is that a relative sparse feeding network can be used, and moreover, a low loss waveguide feeding network can be implemented. However, one has to design a special antenna element having nulls in predefined directions in order to cancel the grating lobes. [1] proposes an antenna array based on one grating lobe reduction where the distance between elements is 1.8λ with elements having nulls at 34° [1] by applying box horn elements. Here we deal, for simplicity, with linear arrays of H-plane coupled elements, and two kinds of elements will be discussed: an element composed of 3 rectangular microstrip patches fed by a 1:3 microstrip divider, and a wire element composed of 1:2 upper divider and two arms. The advantages of the last element are that no substrates are contained, and that the nulls of the element can easily be controlled by adjusting the distance between its arms. The structure of the paper is as follows: in section 2 the geometry of the elements is shown, simulated results are presented in section 3, and the measurements are described in section 4 for the second element. Finally section 5 is for the conclusions.