An electromechanically scannable trough waveguide array

The microwave antenna described utilizes a trough waveguide array feeding a section of a parabolic cylinder. Performance of the antenna, a linear array, depends on several properties of the trough waveguide. Electromechanical scanning of the array is achieved by changing the phase velocity in the guide. To continuously vary the guide wavelength at a suitable rate, two methods are used: (1) rotation of symmetrical structures along a longitudinal axis within the trough waveguide, and (2) mechanical variation of the height of periodic structures located on the top of the center fin of the trough waveguide. Both methods were incorporated in short arrays, and the latter method was also used in a ten-foot long array. Successful operation was obtained with scan angles in excess of 20 degrees. Experimental data for the ten-foot array feeding a parabolic cylinder is presented herein.