Abstract: In a serpentine feed structure for a frequency scanned antenna a switching etwork is provided which allows the serpentine to be fed from either end on alternate or random scans. This variable transmission system significantly increases the frequency bandwidth that must be jammed by detrimental countermeasure systems. The feed switching network comprises first, second and third switching circulators coupled to receive radiant energy from a radar transmit-receive switch and selectively couple this energy to one or the other end of a serpentine feed structure for controlling the direction of electromagnetic radiation energy coupled through the serpentine structure. The serpentine feed structure supplies radiant energy to an antenna array of a frequency scanned antenna for controlling the sector scanning of the antenna. Reversing the direction of energy flow through the serpentine causes a change in the particular frequencies scanning a given sector of the scan.