A helical line scanner for beam steering a linear array

A new type of antenna beam scanner which uses the phasing principle for beam steering a linear array is described. The scanner consists of a bank of helical line trombone phase shifters which provide a variable delay circuit for each element of the linear array. The circuits are ganged mechanically by connecting the slides of the trombone phase shifters to a lever arm drive. Short helix sections concentric with the main lines are used to couple the slide of each trombone phase shifter to the main helical lines. Measurements of phase characteristics, insertion loss, and vswr of the trombone phase shifters have been carried out. Isolation between phase shifting circuits has also been measured. Radiation studies were conducted using a ten-element scanner in conjunction with a vertical slot array antenna having ten bays. Patterns showing beam scanning out to from broadside are included.