Future IoT environment requires billions of wireless sensor nodes where energy consumption of these devices will be a concern. This problem can be solved by harvesting energy from ambient environment to power sensor nodes. Ambient RF and thermal energy have a great potential, as both of them are available in most of the places. When combining these two energy harvesters into one module, optimized design is required. This work presents a heatsink antenna, which serves as a part of a triple-band RF energy harvester (GSM900, GSM1800 and 3G) and as a heatsink which boosts the performance of the thermal energy harvester. The antenna has been designed by using Ansys HFSS and Solidworks in parallel for optimal RF and thermal performances.