This paper presents a compact planar ‌microstrip-fed quasi-fractal antenna for 2-60 GHz microwave and millimeter-wave systems. The ultra-wideband property of the antenna is obtained by accomplished two iterations of Sierpinski circular slots on the circular radiator along with using curve-shaped ground plane. The overall antenna size is 28×28×1.6 mm3 which is printed on FR4 substrate with a dielectric constant of 4.4. The designed antenna with a simple and compact structure provides 187% (reflection coefficient less than −10dB) impedance bandwidth, which can cover S (2-4 GHz), C (4-8 GHz), X (8-12 GHz), Ku (12-18 GHz), K (18-26 GHz), Ka (26-40 GHz), and U (40-60 GHz) frequency bands. Due to small electrical dimension of the designed antenna (0.187 λ× 0.187 λ), a large bandwidth dimension ratio of 5347 is resulted. The numerical outcomes are verified by experimental measurements. Measured data are in good agreement with the simulated results. The frequency- and time-domain characteristics of the antenna including impedance matching, far-field patterns, gain, and group delay are presented and discussed. Results show that the antenna is an excellent radiating component for use in several military and industrial systems.