Design of a phased array antenna for indoor positioning system

Corporate-fed phased array antenna with low beam squint is presented for indoor positioning system. Corporate feeding network has a low phase delay, and scan angle variation corresponding to operational frequency bandwidth is considerably small. Conventional phase shifter with large phase shift range is not suitable for beam steering application because quarter-wavelength transmission line in its reflective network radiates. In order to remove unwanted radiation, equivalent circuit for quarter-wavelength transmission line composed of discrete chip inductors and capacitors is proposed. The proposed phase shifter has maximum relative phase shift of 240 degrees and insertion loss of 3.5 dB +/- 0.5 dB. Scan angle of +/-10 degree is measured when phased array antenna, based on the proposed phase shifter, is scanned in both directions off the broadside. Low beam squint is obtained in the proposed design.