Complete characterisation of leaky-wave antennas based on stepped rectangular waveguides

A complete procedure has been carried out for the analysis and the design of a class of leaky-wave antennas based on `stepped´ rectangular waveguides, introducing a new topology which results quite advantageous in terms of compactness and performances at microwaves and millimetre waves. Useful practical properties of such leaky structures have been emphasised through a parametric analysis; in addition to the basic characterisation of uniform-section antennas, also the effects of the shape tapering have extensively been investigated in order to realise illumination functions that reduce the sidelobes. Then, original synthesis procedures have been implemented in a versatile and efficient program, taking accurately into account the influence on the radiation pattern of the variations in both the attenuation and the phase constants, as the geometric parameters are varied. Different prototypes have been simulated, confirming the remarkable behavioural features for advanced applications of such antennas as frequency-scanned pointed-beam radiators.