Broadband millimeter-wave microstrip comb-line antenna using corporate feeding system

A broadband microstrip comb-line antenna using a novel corporate-feeding system is developed in the millimeter-wave band. The antenna is composed of four linearly-arranged comb-line antennas with traveling-wave excitation fed by a parallel-feeding circuit for tournament configuration. Total phase deviation due to frequency change becomes one fourth of an ordinary series feeding from the edge of the antenna. Furthermore, inner two comb-lines are connected at the overall center of the developed antenna. Therefore, narrowband matching elements are not necessary and amplitude deviation of aperture distribution for input from one-side due to frequency change is compensated by radiation for input from the other side. The effect of the proposed feeding-circuit for broadband operation is confirmed by comparing the measured performance with the antennas fed by other ordinary feeding circuits.