Design considerations for comb line microstrip travelling wave antennas

An efficient design procedure for microstrip stub traveling wave arrays is presented. The design frequency of 24.125 GHz and the desired sidelobe suppression of more than 20 dB demand an accurate array synthesis and a high fabrication accuracy. Special attention is given to the influence of the T-junction which connects the stub to the microstrip feed line and its overall effect on the radiation mechanism. To demonstrate the quality of the design approach several arrays are shown having one or two excitation ports and main beams 45 degrees off broadside. Considering the design frequency of 24.125 GHz, the scan angle of more than 40 degrees off broadside, and the achieved sidelobe suppression, a considerable improvement has been reached compared to the state of the art.<>