Analysis of multiwavelength OOCDMA system with laser phase noise, modal noise, MUI, and receiver noises
✍ Scribed by K. Murugesan; V. C. Ravichandran
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 160 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0895-2477
No coin nor oath required. For personal study only.
✦ Synopsis
These results show that the measured phase tracks the designed phase, and the assumption of 45Њ maximum phase error used in the radiation pattern yield analysis is reasonable.
Conclusions
The design, development, and testing of an X-band 137-element passive reflect array capable of incorporating active devices such as transistor amplifiers has been presented. In this array, dual-feed slotraperture-coupled patch antenna elements are used. The required phase shift to obtain broadside radiation is achieved by sections of transmission lines coupled between two slots. The array features a reasonable interelement spacing that aims at reducing grating lobes. However, the measured radiation patterns reveal significant cross polarization and sidelobes in the copolar pattern. These could be due to the coupling between two slots in individual elements and other phase errors, which occur during the manufacturing process. Further work is required to reduce these undesired features. One possible method to reduce cross polarization is the sequential feeding method.
The presented experimental results have revealed problems of phase errors that affect the radiation pattern of passive reflect arrays. As observed in the presented paper, these errors easily occur at medium and upper microwave frequencies, and they cause an increase in sidelobe levels. It has to be mentioned that this effect can be observed in numerous papers on quasioptical and spatial power combiners, but without mentioning the reason. This paper is one of a few that has identified, named, and analyzed the origin of this problem. This issue may be of even greater significance in active arrays where active elements such as transistor amplifiers can hardly be expected to be identical, and hence readily contribute to random amplitude and phase errors, which affect sidelobes in the radiation pattern.