Western Digital has announced a potential game changer that promises to expand the limits of traditional HDDs to up to 40TBs using a microwave-based write head, and the company says it will be able to the public in 2019. Gizmodo reports: Western Digital's new approach, microwave-assisted magnetic recording (MAMR), can utilize the company's existing production chain to cram a lot more storage onto a 3.5-inch disk. In a technical overview, Western Digital says it has managed to overcome the biggest issue with traditional HDD drive storage -- the size of the write head. These days, an average hard drive maxes out in the 10-14TB range. But by integrating a new write head, "a spin torque oscillator," microwaves can create the energy levels necessary for copying data within a lower magnetic field than was ever previously possible. There's a more thorough white paper for those who want to dive in. According to Western Digital, MAMR has "the capability to extend areal density gains up to 4 Terabits per square inch." By the year 2025, it hopes to be packing 40TBs into the same size drive it offers today.