A substrate-modified CPW-based linear microwave phase shifter.

A novel method for achieving linear phase shift is proposed over the frequency range of 2 - 6 GHz. Dielectric characterization of FR4 substrate interfaced with air as well as water produces the phase shift. The substrate property is modified by introducing a plain rectangular packet and W-shaped packet within the FR4 substrate. The overall dimension of the proposed structure is 30 × 60 mm2. Across the entire proposed frequency range, the reflection coefficient is less than −10 dB. The proposed coplanar waveguide with water- and air-stacked FR4 substrate is simulated, fabricated, and measured for its linear phase shifting characteristics analyzed in ISM 2.45, 3.3, and 5.8 GHz bands. The analysis over the entire band depicts that the differential shift in phase is directly proportional to the effective dielectric constant of the material used. The design will be more useful in automotive anti-collision radars in military, cellular base stations, and satellite communications. [ABSTRACT FROM AUTHOR]