New millimeter-wave leaky-wave antennas

This paper describes a variety of leaky-wave line sources derived from an open waveguide, on which modifications in the cross section are introduced to produce radiation. This allows the control of the leakage rate along the length of the radiator making it possible to shape the radiation pattern. It will be shown that such kinds of structures can profitably be analyzed by considering a suitable equivalent network by which the leaky-wave phase and attenuation constants are calculated. On this basis, different kinds of leaky-wave antennas for millimeter-wave applications are described and the relevant leakage mechanisms discussed. The design procedure for a single radiator will be illustrated, pointing out the advantageous features of the class of antennas considered here. Finally, arrays of leaky-wave line sources will be considered and their two-dimensional scanning characteristics will be discussed. Measurements on prototypes will be provided to validate the theoretical predictions