Planar slotted waveguide array design using the multiport technique

One of the most important features of the Canadian Radarsat synthetic apert ure radar satellite is the 15m.*1.5m. deployable, phase-scanned antenna. Th is paper will describe the design features of that antenna, with particular emphasis on the special techniques that have been developed to analyze and synthesize large slotted waveguide planar arrays. First, the multiport approach to slotted waveguide array design will be int roduced. Both the hardware implementation, with its special test fixture, a nd the underlying analytical algorithms will be described. The latter algor ithms make it possible to analyze the slotted structure taking into account all important mutual coupling effects, and to compute the optimal slot geo metries. The new approach highlights features of the planar array design pr oblem that have not been evidenced with earlier treatments. Moreover, in th e case of a satellite antenna, the method lends itself to rigorous predicti ons of the r.f. performance in the space environment. The performance of the Radarsat EBB (Engineering Bread-Board) and Flight mo dels has been verified by an intensive series of radiation pattern measurem ents, using the spherical and planar near-field techniques. This work has s erved to validate the multiport algorithms. The Radarsat approach to SAR an tenna design is based around thin-wall flangeless aluminum waveguide techno logy. Extensions of the concept provide for dual polarization and dual freq uency bands.