A SINGLE-LAYER LINEAR-TO-CIRCULAR POLARIZATION CONVERTER FOR A NARROW-WALL SLOTTED WAVE-GUIDE ARRAY

This paper describes the characteristics of a one dimensional narrow-w all slotted waveguide array with a single-layer linear-to-circular pol arization converter consisting of a dipole array. An external boundary value problem of one slot and three dipoles, which approximates the m utual coupling between the dipole array and an edge slot extending ove r three faces of a rectangular waveguide, is formulated and analyzed b y the method of moments; design of polarization conversion is conducte d for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due t o the alternating slot angle: these are suppressed in this paper by ch anging the dipole angle and degrading the axial ratio of the unit elem ent. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarizat ion conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.