Four-arm spiral antenna

The invention discloses a four-arm spiral antenna. The four-arm spiral antenna comprises a spiral arm, and the spiral arm comprises a first spiral arm portion, at least one second spiral arm portion arranged at an interval from the first spiral arm portion, and a third spiral arm portion, wherein one end of the first spiral arm portion and one end of the second spiral arm portion are connected with one end of the third spiral arm portion, and the other end of the third spiral arm portion is connected with a spiral arm feed end feeding the spiral arm. The spiral antenna provided by the invention can realize multi-frequency-range work of more than two frequency ranges with quite large frequency intervals and can also adjust input impedance of the spiral antenna through structural adjustment of the spiral arm of the spiral antenna so as to realize impedance match between an input port and a feed pot, reduce energy loss and improve the overall gain of the antenna. The spiral antenna provided by the invention is compact in structure, light in weight, small in volume and easy to process.