A method to optimize the bandwidth of UWB planar monopole antennas

✍ Scribed by D. Valderas; I. Cendoya; R. Berenguer; I. Sancho

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 392 KB
• Volume: 48
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.21291

✦ Synopsis

illumination on S 21 near pinch-off voltage. As the input optical power is increased, the forward gain is also increased. However, the phase of S 21 is insensitive to illumination, as is evident from Figure 4. Further, we plotted the variation in the remaining parameters (S 12 , S 22 ) with illumination near pinch-off. These variations are depicted in Figures 5 and6. We observed few changes due to illumination in S 12 and S 22 , which also qualitatively support the experimental results of [5, 7].

5. CONCLUSION

Different analytical expressions for the photo-dependent intrinsic parameters have been used to study the effect of illumination on the S-parameters of a GaAs MESFET. It has been observed that a considerable amount of changes in S 11 and S 21 may be obtained by changing the level of incident illumination on the device, whereas very few changes are observed in the case of the S 12 -and S 22parameters under the illumination condition. Further, it has been observed that S 11 and S 21 are very sensitive to illumination when the device is operated in the near-pinch-off region. To the best of our knowledge, this is the first analytical model to study the photo-effects on the S-parameters of a GaAs MESFET.