This study investigated a one-dimensional traveling wave waveguide antenna array including two types of longitudinal resonant slots. The slots of the first type are located with the period P1 and are tuned to the resonance frequency f1, and the slots of the second type are located with the period P2 and are tuned to the frequency f2. The periods P1,2 are chosen in such a way that at frequencies f1,2 the antenna emits in the same directions, which are determined by the angle of radiation θp. It has been experimentally shown that an array of this type effectively operates in two sub-ranges in the vicinity of frequencies f1,2 = 9.5 and 10.8 GHz. Moreover, the width of each sub-range is approximately twice wider the operating frequency range of the array with non-resonant radiators.
Bankov et al. (Wed,) studied this question.