This article uses Koch fractals to demonstrate a compact heptagonal wideband antenna for 5G mm-wave applications. This antenna is designed with defective ground planes to enhance impedance matching and employs Koch fractal geometry for wideband characteristics. In terms of performance and wideband features, fractal antennas prove to be more effective than other antennas. This antenna is designed to achieve greater gain and improved bandwidth characteristics while also minimizing interference at higher frequencies. A peak realized gain of 5dBi at 27.58 GHz is observed for the antenna, which offers a bandwidth between 26.5 and 40 GHz. Millimeter-wave integration is well suited to the proposed flexible antenna. A similar response can be found both in the measured results and in the simulated results. It is a compact antenna with a size of 9 mm by 9 mm. With a bandwidth of 7.42GHz, the VSWR for the whole frequency spectrum is less than 2 is achieved with the HFSS Tool. Experiments and simulations yield a good radiation pattern.