Iteration-Free Design of Waveguide Slot Array With Cavities

In the design of large arrays, aperture field distribution control taking the mutual coupling into account is computationally heavy; here iterative design is indispensable especially for the elements in the periphery of the array aperture. This paper presents an iteration-free design for a waveguide slot array by using cavities which stabilize the external mutual coupling of the slots. All cavities have the same dimensions, which realize an active admittance almost equivalent to that of isolated slots in a half-free space. They are almost constant for the slot parameters and also insensitive to the environment of adjacent elements. This suggests that a slot could be designed independently of neighboring slots, irrespective of the position in the array, as if it is isolated in the half-free space. This dispenses with the time-consuming iterative procedure. Uniform and Taylor distributions with dB sidelobes were designed to demonstrate this iteration-free design. A HFSS simulation predicts a high gain of 32.6 dB and a high aperture efficiency of 88.4% using the cavities for the uniform distribution, while measurements for the Taylor distribution using cavities demonstrates that the sidelobe levels are dB and dB in the H-plane and dB in the E-plane.