A slot-based miniaturized antenna design for CubeSat applications that operate in ultra high frequency (UHF) band is presented. The proposed antenna design consists of a frequency reconfigurable (FR) slot-based antenna integrated on a Rogers RO4350 substrate. The frequency range covered by the FR antenna is 300-450 MHz. A single varactor diode is used to sweep the frequency of the design. The proposed meandered loop-slot antenna design is small in size and has planar geometry with overall substrate dimensions of 100 × 100 mm 2 . The proposed downsized antenna with frequency reconfigurability is ideally suited for small satellite applications in the UHF band, especially CubeSats.