A graphical method to design radiating elements for phased-array antennas

Planar phased arrays used in modern 3D radar systems need to have a wide bandwidth and a wide coverage region. Thus the design of arrays for such applications is a very intriguing task. Additional constraints to be taken into account during the design are: the lattice spacing must be wide to reduce the number of radiating elements, but sufficiently small to avoid grating lobes and blind spots inside the coverage region; the array needs to be covered by a dielectric cover which protects the array surface, facilitates the matching of the radiating element and does not disturb radiation; the radiating element must be small enough to meet the lattice dimensions. This paper reports a graphical method (made up of cover graphs and an impedance matching graph) useful to design waveguide radiating elements and the dielectric cover, while taking into account the aforementioned constraints.