This paper proposes an ultra-broadband (2–13 GHz) and low-profile log-period monopole end-fire antenna for the flush-mounted applications. 24 monopoles with a log-period rule are used to cover the whole operating frequency band, and those monopoles are printed on both sides of a low-loss dielectric layer vertically placed over a slot feeding line with wideband microstrip-to-slotline transition. The low profile is realized by bending the parts of the long monopoles so that the overall antenna size is obtained as 40 mm × 100 mm × 13.6 mm. The proposed antenna is fabricated, and the measured results agree with the simulated results very well. The measured results indicate that the proposed antenna can work at the whole 2–13 GHz band with very good end-fire radiation patterns and stable gain performances.