Flat-top directional diagram millimeter wave radar antenna and system

The invention discloses a flat-top directional diagram millimeter wave radar antenna and system. The flat-top directional diagram millimeter wave radar antenna comprises a dielectric substrate, an antenna array and a feed network, wherein the antenna array and the feed network are arranged on the front side of the dielectric substrate; the antenna array comprises n serial feed line arrays, and the back surface of the dielectric substrate is equivalent to a grounding surface; the n series-feed line arrays are fed in parallel through the feed network, and each series-feed line array which is fed in parallel has excitation distribution forming a flat-top directional diagram; each series feed line array is formed by series feed of m radiation units, and series feed line array units have Chebyshev excitation distribution; wherein an impedance transformer is arranged between the series feed line array and the feed network, and the impedance transformer is used for carrying out impedance matching on the series feed