This　paper　presents　a　wideband　antenna　consisting　of　two　series-fed　fan-shaped　bowtie　dipole　antenna　elements　and　an　integrated　tapered　balun　for　through-the-wall　imaging　radar　(TWIR)　applications.　The　two　fan-shaped　bowtie　dipole　antenna　elements　with　different　radii　and　same　flare　angle　are　connected　using　a　coplanar　stripline　and　backed　by　a　ground　reflector.　The　balun　realized　by　a　tapered　microstrip　line　and　a　slot　line　is　used　to　feed　the　antenna.　The　proposed　antenna　has　been　numerically　investigated,　which　shows　that　a　10-dB　impedance　bandwidth　of　85.9%　ranging　from　1.38　to　3.46　GHz　is　attained.　The　overall　size　of　the　proposed　antenna　is　1.2　lambda　x　0.8　lambda.　The　radiation　patterns　are　roughly　stable　over　the　operating　bandwidth　with　nearly　endfire　characteristic.