Low cost beam-steering approach for a series-fed array

Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex and costly. This paper presents a concept which overcomes these detrimental attributes by eliminating all of the phased array backend (including phase shifters). Instead, a propagation constant reconfigurable transmission line in a series fed array arrangement is used to allow phase shifting with one small (≤100mil) linear mechanical motion. A novel slotted coplanar stripline design improves on previous transmission lines by demonstrating a greater control of propagation constant, thus allowing practical prototypes to be built. Also, beam steering pattern control is explored. We show that with correct choice of line impedance, pattern control is possible for all scan angles. A 20 element array scanning from -25° ≤ Θ ≤ 21° with mostly uniform gain at 13GHz is presented. Measured patterns show a reduced scan range of 12° ≤ Θ ≤ 25° due to a correctable manufacturing error as verified by simulation. Beam squint is measured to be ±2.5° for a 600MHz bandwidth and cross-pol is measured to be at least -15dB.