This paper proposes a new frequency-reconfigurable antenna (FRA) which consists of quasi-Sierpinski fractal dipoles integrating with a dual-band high-impedance surface (HIS). The antenna can operate in three frequency bands, i.e., X-band, Ku-band, and Ka-band, by changing the states of two switches. In order to achieve a low-profile design and good front-to-back radiation ratio, a dual-band HIS is presented as a reflector. The HIS is composed of an array of square patches with etching square slots, which has two in-phase reflection bands for X-band and Ku-band and can be viewed as an artificial magnetic conductor, while as a metallic electric conductor in Ka-band. So the antenna has a unified profile of 2 mm for different reconfigurable frequency bands. An ideal switch prototype of FRA was simulated, and practical PIN switch models of FRA and 2 2 FRA array with bias lines were fabricated and tested to verify the reconfigurable property of the proposed antenna.