A novel reconfigurable antenna covering an 11.5:1 bandwidth is designed and fabricated for cognitive radio applications. The proposed novel antenna has two independent paths to cover 430 MHz to 5 GHz frequency range. The first path is directly connected to an ultrawideband antenna, which covers 1–5 GHz operation frequency range. The second path, for the frequency range between 430 MHz and 1 GHz, goes through a dc-controlled varactor-based matching network. The switching functionality between wideband (1 to 5 GHz) and reconfigurable region (430 MHz to 1 GHz) is realized by two discrete switches. The designed antenna has a simple structure and compact size of 60 mm $\times100$ mm. The proposed novel antenna has great potential for use in cognitive radio systems.