Advanced Driver Assistance Systems (ADAS) is currently the focus of automotive safety protection technology, in which the millimeter-wave automotive radar must be used. In addition, since the millimeter-wave band can provide large bandwidth, B5G/6G mobile communications will also develop in millimeter-wave band. This project designs microwave and millimeter-wave high-gain low-sidelobe harmonic-suppressed wideband array antenna using high-order mode patches, dipoles, slots, and parasitic elements, which can be used in microwave and millimeter wave wireless communication systems, and automotive radar systems.