The investigation of oil palm ash microwave absorbers involves the design, simulation and fabrication of an effective broadband frequency for anechoic chamber. The resistive and magnetic materials in the oil palm ash compose its potential to be used as microwave absorbing materials. These oil palm ash absorbers are simulated using CST Microwave Studio. The arch measurement is executed to investigate the reflectivity performance of the oil palm ash absorbers. These absorbers are designed to operate effectively between the frequencies of 8 GHz and 12 GHz for broadband application.