In this paper, a new reconfigurable microstrip fractal ultra-wideband antenna with a capability of variable rejection frequency bands is presented. The main patch of this antenna has two modified C-shaped gaps. Also, on these c-shaped gaps, 10 ideal MEMS switches are used to produce band-notch frequencies at six different frequencies of: 5.4 GHz (5.2–5.5), 5.8 GHz (5.7–5.9), 6.1 GHz (5.9–6.3), 7 GHz (6.9–7.2), 7.9 GHz (7.7–8.1), and 8.4 GHz (8.2–8.6). This antenna is fed by a 50 Ω microstrip line and works in a wide bandwidth of 2.9–11 GHz. The antenna is designed and fabricated on an inexpensive substrate of FR4. Dimensions of the antenna are 31.2 × 38.4 mm. Measurement and simulation results are in good agreement.