This invention relates to a radio antenna as a transmitting antenna or a receiving antenna and a mobile radio system. In accordance with the invention, the radio antenna (MS-A, BTS-A) is a planar antenna and consists of one carrier part (1) of an electrically insulating material, of a coating (s) applied thereon and of two spaced coating feeders (3, 4) having an electrical connection to the interstitial coating (2). This coating is made of a coating material, which consists of specific materials in indicated amounts of substances of one binding agent, insulator, dispersing agent and distilled water. By means of the coating (2), electromagnetic waves are transmittable or receivable with a high frequency selectivity being possible in combination with a spherical characteristic.