Abstract: Kerkenes Mountain in Central North Tukey was a very large iron-age settlement of Persians. It is located at about 30 km south east of the town of Yozgat. Archaeogeophysical surveys have been carried out in the site along with the archaeological works since 1993. The site was surveyed by a Geoscan gradiometer almost throughout. However, some form of noise was introduced in the gradiometer measurements. In this paper, the noise introduced, was filtered out by designing a wavenumber filter. Filtered maps show improved images of the response of manmade structures.