Extraction of complex resonances associated with buried targets

Early time returns affect the estimation of complex natural resonance (CNR) frequencies associated with a target. This is especially true when there is a small separation between the early time returns and the late time response of the target and the CNRs are low Q mechanisms. A good example of this scenario is antipersonnel mines. In this situation, it helps to remove the early time returns from the total scattered field. A new technique to accomplish this is presented here. Using some numerical data and some experimental data, it is demonstrated that this technique is very effective in removing the early time returns. The modified scattered field data then yields better estimates of CNR frequencies.