Mitsubishi Electric Corporation has developed a slotted waveguide array antenna made of injection-molded resin which have been demonstrated to outperform conventional patch array antenna in side-lobe characteristics, cross-polarization characteristics and electric power efficiency, as well as offer reduced weight and cost. Mitsubishi Electric’s new antenna will enable radar systems to achieve enhanced observation range and accuracy and wireless communication systems to achieve greater communication capacity and speed. The company will now begin deploying the antenna for various applications, including as weather, airport radar remote-sensing radar and satellite communications.
The antenna is made with resin injection molding for reduced weight and low cost. Resin, however, is easily distorted by heat compared to metal, so resin-molding waveguide parts must be secured with screws, which require screw-holes that can degrade the antenna’s electric performance. Mitsubishi Electric solved this problem with a proprietary “boss-iris structure,” which incorporates small, round “boss” protuberances for screw holes and an “iris” diaphragm waveguide to adjust electrical characteristics (part of the boss and the rib structure serve as the iris). The antenna also achieves industry-leading performance thanks to the proprietary structures: “boss-iris structure” and “novel ridge structure” which is a fence meandering along the waveguide to control finely the radiation from the slots. As a result, the new antenna’s injection-molded design maintains high performance as well as weighs 40 percent less and costs 90 percent less than conventional metallic versions.
Mitsubishi Electric developed the antenna with Hiroshima Institute of Technology, and received support from the Japan Science and Technology Agency’s A-STEP program under a project entitled “Development of a novel resin ridge waveguide antenna with eminent low sidelobe.” For the project, a large-scale array antenna prototype consisting of about 2,000 elements was manufactured and evaluated. In tests, the antenna demonstrated high performance, including 60 percent suppression of sidelobe, 90 percent reduction of cross polarization, and 10 percent greater electric power efficiency compared to conventional patch array antenna.