Growth and studies of optical properties of double‐doped In:Fe:LiTaO₃ crystal

Abstract

to the flat bottom dielectric slabs, and tested them with a 4 ϫ 2 array antenna. This modification makes the shape of slabs similar to the one shown in Figure 8. Figure 9 shows the H-plane radiation patterns of three cases. With the addition of small notches, the antenna beam can now be scanned up to ϩ40°. CONCLUSIONSA novel design of a steerable array antenna has been demonstrated. The phase shifter is based on a movable dielectric slab placed close to a CPW with air gaps. The impedance mismatch can be avoided by choosing the slab dielectric constant and length for the two extreme positions, namely at d ϭ 0 and d 2 mm. It may be possible to further reduce S 11 by optimizing the impedance mismatching position at d Ͼ 0 instead of d ϭ 0. We also show that the use of preset delay lines can reduce the number of phase shifters. Although the test antenna is designed for 5.8 GHz, the technique can be applied at a much higher frequency. One possible application is for the 77 GHz automobile collision avoidance radar [6]. ACKNOWLEDGMENTSThis project was supported by National Science Foundation ECS-0424414. The authors thank J. Kajiya and J. Ritcey for useful discussions and suggestions. GROWTH AND STUDIES OF OPTICAL PROPERTIES OF DOUBLE-DOPED