An error estimator for the moment method in electromagnetic scattering

✍ Scribed by Xin Wang; Matthys M. Botha; Jian-Ming Jin

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 282 KB
• Volume: 44
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.20623

✦ Synopsis

electric field is aligned along the dipole array, the array is as designed, thus absorbing the incident energy. For the case when the incident electric field is orthogonal to the dipole elements, reflection occurs due to the combination of the high dielectric constant of the substrate material r ϭ 11.9, and the wafer ground plane.

Next, the printed dipole array and the superstrate were stacked in air, at a separation distance of 1.5 cm, 0.5 at 10 GHz [Fig. 1(d)]. The arrangement was then illuminated in order to observe the effect that optically induced switching has upon the performance of the system, which is now configured as a microwave reflector/absorber optically controlled shutter surface.

The performance of the shutter was tested, as shown in Figure 4, and it was observed that under the dark condition (superstrate transparent to microwave energy), the assembly worked as an absorber (compare with Fig. 3). The resonant frequency of the shutter arrangement has been slightly reduced to 50 MHz due to coupling between the antenna array and the superstrate. Under illumination conditions, plasma is formed in the Si superstrate wafer and it becomes more reflective (Fig. 4). These results shown that a switching range of approximately Ϫ25 dB can be achieved through this shutter mechanism.

4. CONCLUSION

A wafer-scale optically controlled dual stacked high-resistivity Si wafer-scale system has been presented for its potential as an integrated absorber/reflector mechanism. Around 25-dB switching isolation between light ON and light OFF states has been demonstrated. Such a device can find utility in radar applications where agile radar cross-section modification is required, or in applications were spatial amplitude modulation of a microwave signal, without the need for electrical interconnects, is required.