FERROELECTRIC PHASE SHIFTERS AND THEIR PERFORMANCE IN MICROWAVE PHASED-ARRAY ANTENNAS

Recent advances in the development of Barium Strontium Titanate ferroe lectric composition has made possible reasonable performance of ferroe lectric phase shifters to frequencies up to 10 GHz. These material imp rovements, coupled with phase shifter circuit design changes have resu lted in phase shifts greater than 360 degrees with less than 6 dB inse rtion loss. In particular additives to the BaxSr1-xTiO3 composition ha ve been shown to exhibit a consistent electrical phase shift verses DC potential over parameters of temperature and humidity. These ferroele ctric material improvements and circuit design changes, included with the development of multiple ferroelectric phase shifters makes possibl e the fabrication of a low cost electronic scanning antenna. A single four element phase shifter was used with a one dimensional linear ante nna array which was constructed on three layers and used an aperture c oupled distribution technique. Individual elements of this multiple fo ur element phase shifter were evaluated with respect to uniformity pha se shift and insertion loss. The four element antenna was fed by four ferroelectric phase shifters and the phase shifters are corporately fe d by the microwave source. The ferroelectric phase shifters are contro lled via a dedicated microcontroller which calibrates out element phas e variations and provides a real time scan capability for the antenna assembly.