An antenna is provided, comprising a reflector, a director; a first tapered microstrip line, a transition structure, a second tapered microstrip line, and a dipole radiator; wherein the transition structure has a main body of a parallelogram shape having a first side connected to the first tapered microstrip line, a second side opposite to the first side and connected to the second tapered microstrip line, a third side connecting the first side and the second side, and a fourth side connecting the first side and the second side, the third side being opposite to the fourth side; and the transition structure comprises a plurality of teeth connected to and extending away from at least the fourth side of the main body.