Three variations of a pattern-reconfigurable microstrip parasitic array

✍ Scribed by S. Zhang; G. H. Huff; G. Cung; J. T. Bernhard

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 304 KB
• Volume: 45
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.20826

✦ Synopsis

dB for a height of 2.2 mm, and the angle range within the axial ratio is less than 3 dB for 80°at a height of 2.4 mm.

A survey about the influence of the holes' radii has led to the same conclusion: a minimum radius is required in order to obtain circular polarization. Furthermore, we note that the adaptation depends on the height of coaxial probe. We also note that, for a large radius, the bandwidth is about 10%, but the circular polarization exists in only one plane.

The circular-polarization quality depends strongly on the holes' dimensions. In addition to that, a minimum radius and a minimum height are required in order to make the antenna circularly polarized. With regard to the return loss of the structure, it is independent of the quality of the polarization. Thus, an optimal configuration of the antenna feed and the holes' dimensions needs to be found.

The incidence of the holes' position is now examined. When L h decreases, the coaxial-probe height does not have incidence on either the antenna adaptation or the axial ratio. However, if the probe is set closer to the external cylinder edge, the axial ratio is altered. The minimum axial ratio obtained is 0.006 dB for r p ϭ 1.7 mm. For r p ϭ 1.1 mm, the axial-ratio minimum is 0.17 dB and is less than 3 dB for a range angle of 95°.

CONCLUSION

A new and original concept of a circularly polarized DRA has been proposed. By introducing four identical holes in the resonator, a good circular polarization can be achieved, since we can obtain a minimum axial ratio of 0.006 dB. The concept of such an antenna is designed by optimizing the geometrical characteristics of the structure. Either the quality of polarization or the adaptation of the antenna depend strongly on the position and dimensions of holes and the coaxial probe.