Microwave absorbers or Radiation Absorbent Materials-RAM are normally made of blocks of wave-absorptive material to avoid the reflection of electromagnetic waves incidental on it. Mainly used in anechoic chambers, it comes in various designs such as pyramidal absorber, twisted pyramidal absorber, hollow pyramidal absorber, wedge absorber, multilayer dielectric absorber, and hybrid dielectric absorber, among others. This paper presents a new concept for RAMs applying corrugated surfaces to improve reflectivity. A simulation work in determining the effect of corrugated walls on the absorption performance of microwave wedge absorbers is presented. The conditions are different corrugations depth, density depth and lastly the distance between signal source and wedge microwave absorber. These microwave absorbers are also simulated in CST Microwave Studio in the frequency range of 0.1 GHz to 5 GHz. Results so far have indicated good agreement with the required average values for a good performance for a microwave absorber. © 2011 IEEE. 556560Christopher, L.H., Ronald, R.D., Comparison of electromagnetic absorber used in anechoic and semi-anechoic chambers for emissions and immunity of digital devices (1994) IEEE Trans. Electromag. Compat., 104 (1), pp. 307-313. , NovNornikman, H., Malek, F., Soh, P.J., Azremi, A.A.H., Wee, F.H., Hasnain, A., Parametric studies of pyramidal microwave absorber using rice husk (2010) Progress in Electromagnetics Research, 104, pp. 145-166Christopher, L.H., Ronald, R.D., A low-frequency model for wedge or pyramid absorber arrays-ii: Computed and measured results (1994) IEEE Trans. Electromag. Compat., 36 (4), pp. 307-313. , NovDawson, J.F., Ahmadi, J., Marvin, A., Reduction of Radiated Emissions from Apertures in Resonant Enclosures by the Use Absorptive MaterialsCalame, J.P., Wesley, G.L., A modified method for producing carbon-loaded vacuum-compatible microwave absorbers from a porous ceramic (1991) IEEE Trans. on Electron Devices, 38 (6), pp. 1538-1543. , JuneNornikman, H., Soh, P.J., Azremi, A.A.H., Performance of different polygonal microwave absorber designs using novel materials Int. Symp. on Antennas and Propagat., Bangkok, Thailand, Oct. 20-23 2009, pp. 1151-1154Ellam, T., An update on the design and synthesis of compact absorber for emc chamber applications Proc. IEEE Int. Symp. Electromag. Compat., Chicago, IL, Aug. 22-26 1994, pp. 408-412Ishino, K., Morikawa, T., Saito, T., Hashimoto, Y., Shimizu, Y., Realization of compact semi- and fully anechoic chambers using a new developed composite absorber Proc. IEEE Int. Symp. Electromag. Compat., Chicago, IL, Aug. 22-26 1994, pp. 413-418Balanis, C.A., (1997) Antenna Theory: Analysis and Design, , 2nd ed. John Wiley SonsAnzai, H., Saikawa, M., Naito, Y., Mizumoto, T., The equivalent representation of pyramidal absorbers at its application to the analysis of electromagnetic wave absorber's characteristic IEEE International Symposium on Electromagnetic Compatibility, Atlanta, GA, Aug. 1995, pp. 563-567Nornikman, H., Malek, F., Soh, P.J., Azremi, A.A.H., Effect on source signal condition for pyramidal microwave absorber performance Int. Conf. on Computer and Communication Eng., Kuala Lumpur, Malaysia, May 11-13 2010, pp. 1-5Khajehpour, A., Mirtaheri, S.A., Analysis of pyramid em wave absorber by fdtd method and comparing with capacitance and homogenization methods (2008) Progress in Electromagnetics Research Letters, 3 (5), pp. 123-131. , OctRazavi, S.M.J., Khalaj-Amirhosseini, M., Optimization an anechoic chamber with ray-tracing and genetic algorithms (2008) Progress in Electromagnetics Research B, 9 (6), pp. 53-68Chung, B.-K., Chuah, H.-T., Modelling of rf absorber for application in the design of anechoic chamber (2003) Progress in Electromagnetic Research, PIER, 43 (6), pp. 273-285. , DecLeon Fernandez, G., Loredo, S., Zapatero, S., Las-Heras, F., Radiation pattern retrieval in non-anechoic chambers using the matrix pencil algorithm (2009) Progress in Electromagnetics Research Letters, 9, pp. 119-127Mentzer, C.A., Leon Peters, J., Properties of cutoff corrugated surfaces for corrugated horn design (1974) IEEE Trans. on Antennas and Propag., AP-22 (2), pp. 191-196