5G communication technology is used in very demanding applications, such as high-performance mobile devices, Internet of Things (IoT) applications, and wearable devices. Therefore, unlike the previous technologies, 5G technology requires massive bandwidth, mainly within three key frequency ranges, Sub-1 GHz, 1-6 GHz, and above 6 GHz. However, these challenges require more accurate and wide-band characterization of the circuits designed for 5G systems. To be specific, the losses, which can be neglected at lower frequencies, may substantially affect the performance of these circuits in the high frequency bands. This requires a comprehensive understanding and proper characterization of the loss mechanism within all frequency band of 5G. This paper investigates the viability of using the most common and easily accessible material FR-4 in circuits designed for 5G applications, and thus focuses on the proper modeling of the microstrip lines built around FR-4. For this purpose, we have used the fractionalorder model of the lossy dielectric material, and ended up with a more accurate and simple model which fits well within a wide frequency range, from 1GHz to 16GHz.