Untilted edge-slot antenna arrays fed by wiggly double-ridged waveguide

A new method is proposed to feed untilted edge slots using a wiggly double-ridged waveguide. The ridges have constant heights nearby each slot, but the heights of the ridges vary linearly from each slot towards the vicinity of adjacent slots. The heights of the ridges vary alternatively for successive slots whereas gap spacing between the upper and the lower ridges are constant. It is shown that by changing the wiggle depth, the radiated energy of the proposed untilted edge slot can be controlled. An appropriate equivalent circuit is employed for the proposed slot antenna and values of the elements of the equivalent circuit are derived by sweeping slot depths and wiggle depths. A linear array consists of 11 slots are then designed based on the proposed equivalent circuit to achieve -20 dB of side-lobe level. The designed array is constructed and tested. There is an agreement between the simulation and the measurement results that indicates the effectiveness of the proposed untilted slot.