Shaped Continuous Parallel Plate Delay Lens With Enhanced Scanning Performance

In this paper, shaped continuous parallel plate waveguide delay lenses are proposed. The previous configurations introduced by the authors displayed a residual side lobe imbalance, showing the limitations of elliptical delay lens profiles, derived from a starting bifocal constrained lens. Polynomial profiles are proposed here as a way to enhance the scanning performance and the pattern shape. Optimized configurations demonstrate a reduction in the phase aberration levels over a large scanning range ([-30°, 30°]). The associated radiation patterns demonstrate lower and more balanced first side lobe levels (SLLs) (≅ -18 dB), as compared to the previous elliptical approach (≅ -13.2 dB). A validation has been proposed through the manufacturing and test of a prototype over the downlink Ka-band ([27.5-31] GHz). Excellent radiation performance [half-power beamwidth (HPBW), SLL] has been experimentally obtained over a wide angular range ([-31.5°, 31.5°]), including low scanning loss and high radiation stability over the entire frequency range. High radiation efficiencies are demonstrated with this fully metallic design, particularly suitable for space applications. The mechanical simplicity offered by the concept is also quite attractive for low-cost multi-beam platforms.