Indonesia’s geographical location supports the existence of various coffee commodities. As a plantation commodity, coffee has a high economic value. Coffee has a lot of substance that is beneficial to the body, one of is caffeine that serve to increase the stamina. Caffeine is naturally present in many types of plants as secondary metabolism. This research was done to know the content of caffeine in a local Arabica pure coffee with their variation of roasted temperatures. Coffee roasting is a stage of processing coffee beans into ready to grind, which can produce variations in the taste and content of coffee. The roasting process uses a roasting machine that automatically adjusts the roast temperature. Variations of roasted coffee are ground and used as a solution to determine the caffeine content. The determination of the coffee content is carried out using the spectrophotometric method, which measures the absorbance of caffeine in solution when it is passed by electromagnetic waves in the UV-Vis spectrum. The test results showed that the highest caffeine content was on samples of pure Arabica coffee with a roasted temperature of 195°C to 215°C with five levels of coffee roast. Caffeine content in sequential 3.217% and 2.597%.

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It is challenging to picture the physical phenomenon known as electromagnetic wave simulation. The purpose of this work is to model the propagation of electromagnetic waves on a two-dimensional medium. FDTD is a method that is quite relevant to be used in visualizing electromagnetic waves. One can utilise Maxwell's equations to describe discrete electromagnetic waves having TM mode. The simulation is in the form of a Gaussian pulse with the magnetic field H and the electric field E having position and time domains, respectively. The proposed simulation conditions have considered the program's boundary conditions and numerical stability. The differential equation method methodology is used in the FDTD method. The simulation results show that the wave without PML is impeccably reflected, and with PML, the wave is reflected by the material utilized. Materials with high conductivity will make the waves decay and reduce their intensity. This research can be used in the investigation of materials and communication media innovation.