Antenna array beam-steering by the integration of a series phase shifter

Abstract

Beam steering is defined as the ability to electronically steer the beam maximum of an antenna electric field pattern to some predefined point in space. Leaky wave antennas can be used for such a purpose but include inherent problems such as large size, difficulty in impedance matching and a large number of sidelobes in the resultant electric field pattern. This paper concentrates on a method for mimicking the operation of a typical leaky wave antenna array by the simple integration of a phase shifter into the array structure. Up to 12/spl deg/ beam steer is demonstrated using the integrated array whose structure is short and compact compared to the typical leaky wave arrays. The bias voltage of the phase shifter is used to control the impedance match of the array reducing the VSWR to below 1.5 where the 12/spl deg/ beam steer is experienced. The phase shift between the elements of the array, used to provide beam steering, is provided by scanning the frequency through a range of frequencies from 1.17 GHz to 1.23 GHz. This range is greatly reduced from typical leaky wave antenna arrays because the phase shifter also acts to provide an additional phase shift between the elements. The resultant radiation patterns also show improved characteristics as the number of sidelobes has been decreased.