A novel feed system for circular arrays enabling beam steering over 360° in the azimuth plane with a stable scanned beam is proposed. It consists of rotating and fixed parts. The rotating part is a two‐dimensional offset fed parabolic reflector which is inside a circular parallel plate waveguide. The power coming from the rotating part is coupled with the elements of the circular array through a fixed coupling structure. The rotating part is light and its moment of inertia is significantly less than the conventional rotating antenna systems for beam scanning. Therefore, the beam can be steered much faster than the current rotating antenna systems. The details of the structure including the rotating and the fixed parts are presented and a design procedure for the fixed coupling section is suggested. The performance of the feed system is investigated by simulations and measurements. It is shown that the simulations and experimental results are in good agreement.

A new type of frequency scanning slot array antenna using composite right/left‐handed (CRLH) waveguide as a feeding structure is presented in this study. The waveguide is loaded periodically with short‐circuited air‐filled double‐ridge stubs, which permit the CRLH propagation. The feeding structure is highly dispersive in order to scan a wide angular sector with a narrow frequency sweep. It also easily allows amplitude tapering of the array elements. An eight‐element longitudinal slot array designed for X‐band operation with −22 dB sidelobe level has been built and tested. Good agreement between simulations and measurements was obtained. The structure exhibits 31° of scanning over a frequency bandwidth of only 6%, and low return loss in its band of operation.

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