Advances in non-linear apodization

Abstract

Selected new methods and applications of non-linear apodization for irre gula rly-shaped and parse coherent apertures and arrays are presented. The benefits include unproved impulse response performance, i.e., reduced peak sidelobes and integrated sidelobe power, along with impr oved mainlobe res olution, compared to classic windowing techniques. Non-linear apodization (NLA) techniques can also strve as powerful engines for effective superresolution and bandwidth extrapolation of coherent data for filling spars e apertures. The sparse aperture filling property of superresolution algorithms for radar data forms the basis for a new concept which is introd uced here: Synthetic Multiple Aperture Radar Technology (SMART). Increased swath and/or reduced antenna size are some of the benefits postu lated for SMART applied to synthetic aperture radar (SAR) systems. The benefits of the se new methods and applications for non-linear apodization are then demonstrated for two specific applications: 1) sidelobe control for Y -type synthetic aperture radiometers, such as the European Soil Moisture and Ocean Salinity (SMOS) system [12] and JPL's propos ed GeoSTAR [13] concept; and, 2) ftlling of spa rse synthetic apertur e radar data by exploiting the band width extrapolation properties of non-linear apodization based superresolution techniques. The methods that have been developed and demonstrated herein have potential application to a wide range of passive and active microwave remote sensing and radar systems.