Utilization of higher-mode resonance in broadening the E-plane HPBW of printed antenna for automotive radar application

In this paper, a utilization of higher-mode resonance in broadening the E-plane HPBW of printed antenna is presented. We have combined the dominant TM010 mode resonance of inner resonator with the higher-mode resonance of outer resonator at same frequency level, in order to modify E-plane beamwidth, gain (E & H plane) and radiation efficiency of higher-mode resonance of outer resonator. To generate both modes at the same frequency, a quad-split ring shape patch is placed around the edges of inner patch antenna and single gap coupled microstrip feed is employed between the two resonators. The E-plane radiation pattern of the outer resonator (having dip at 0°) is combined with a directional E-plane radiation pattern of inner resonator due to same polarization level of both resonators. By using the above technique, up to 37.2 % increase in E-plane beamwidth (as compared to conventional patch antenna) and 71.5 % radiation efficiency is achieved.