A processor implemented method for detecting a desired object from an object under test occluded by packaging, comprising: scanning, via one or more hardware processors, the object under test packed inside a package positioned on a conveyer using ultra-wide band signals of an antenna-radar unit mounted on a scanning chamber; receiving, via the one or more hardware processors, a plurality of back-scattered signals from the object under test by the antenna-radar unit; and characterized in that: processing, via the one or more hardware processors, the plurality of back-scattered signals using a first approach to detect whether the object under test is the desired object, wherein the first approach is applied when the object under test is having continuous motion across the scanning chamber, wherein processing via the first approach comprises: (a) processing, the plurality of back-scattered signals by applying a four-tap difference filter to obtain a motion-filtered data matrix; (b) applying, a low pass filter, on the motion-filtered data matrix to obtain an enveloped motion-filtered data matrix; (c) applying, a sliding constant false alarm rate (CFAR) on the enveloped motion-filtered data matrix to determine a detection threshold value; and (d) detecting, whether the object under test is the desired object based on whether an intensity of the plurality back-scattered signals exceeds the detection threshold value. scanning, via one or more hardware processors, the object under test packed inside a package positioned on a conveyer using ultra-wide band signals of an antenna-radar unit mounted on a scanning chamber; receiving, via the one or more hardware processors, a plurality of back-scattered signals from the object under test by the antenna-radar unit; and characterized in that: processing, via the one or more hardware processors, the plurality of back-scattered signals using a first approach to detect whether the object under test is the desired object, wherein the first approach is applied when the object under test is having continuous motion across the scanning chamber, wherein processing via the first approach comprises: (a) processing, the plurality of back-scattered signals by applying a four-tap difference filter to obtain a motion-filtered data matrix; (b) applying, a low pass filter, on the motion-filtered data matrix to obtain an enveloped motion-filtered data matrix; (c) applying, a sliding constant false alarm rate (CFAR) on the enveloped motion-filtered data matrix to determine a detection threshold value; and (d) detecting, whether the object under test is the desired object based on whether an intensity of the plurality back-scattered signals exceeds the detection threshold value. (a) processing, the plurality of back-scattered signals by applying a four-tap difference filter to obtain a motion-filtered data matrix; (b) applying, a low pass filter, on the motion-filtered data matrix to obtain an enveloped motion-filtered data matrix; (c) applying, a sliding constant false alarm rate (CFAR) on the enveloped motion-filtered data matrix to determine a detection threshold value; and (d) detecting, whether the object under test is the desired object based on whether an intensity of the plurality back-scattered signals exceeds the detection threshold value.