A study within the projects "Modeling of target and background for radar frequencies" and "Electromagnetic calculations" (EMB) have been made of the Iterative Physical Optics method (IPO). The benefits of the method are that it is relatively fast and less memory demanding than "exact" methods such as the Method of Moments, Finite Element Method and the Finite Difference Time Domain Method. This makes the IPOmethod suitable for using on objects that are too large for "exact" methods and where high frequency methods not provide results good enough. The IPO-method has been validated against measurements and show very good agreement with measurement data.