Design Of Basestation Antenna Phase Shifter And UWB Bow-Tie Antenna

The electrically adjustable antennas have been widely used as basestation antennas in 3G mobile telecommunication system so as to tune the down-tilt beam and optimize network coverage. Phase shifter is one of the most important components for the electrically adjustable antenna. High-accuracy and low-cost phase shifter which is easy to integrate with basestation antennas is generally desired for basestation antenna phase shifter. Basing on these requirements, classical arc shaped suspended T-junction basestation antenna phase shifter is improved in the first part of the paper, and a novel moveable dielectric plate phase shifter is proposed and designed for 3G basestation antennas.The basic principle for microwave phase shifter and the theory of beam electrically adjustment are introduced firstly. Then we optimize the classical arc shaped suspended T-junction basestation antenna phase shifter, according to make the plate as multilevel impedance transformation structure, design the plate situated between the two arcs as tapered change structure and add a one quarter branch, wideband impedance matching for the phase shifter is improved. A novel phase shifter with moveable dielectric wedge plate sandwiching the strip line in a tri-plate transmission line structure is further proposed and designed for 3G basestation antenna. Saw-tooth shaped wedge dielectric is used in order to minimize impedance mismatching. Numerical simulations indicate that phase shifter unit with saw-tooth shaped wedge dielectric may provide low return loss and insertion loss, and also can get high-accuracy shifting phases. The performance of the proposed wedge dielectric phase shifter is demonstrated by a four-element 3G linear array. Beam tilting in the vertical plane of the basestation antenna in a range of 0.2°to 12°can be obtained. Therefore the novel dielectric wedge phase shifter holds high engineering value.Ultra-wide band telecommunication (UWB) radio is a promising technology in recent years. Since wide frequency bands, quasi-omnidirectional radiation pattern and small size are required, antenna design is a challenge for UWB communication technology. In the second part of the paper. Bow-tie UWB antenna is researched and developed. By turning overlapping with the two arms, and using tapered change for the width of lower arm to plan the UWB matching network appropriately, Bow-tie UWB antenna is designed successfully. The test shows that the antenna can work in the range of 3.1 GHz to 10.6GHz.