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IEEE Transactions on Antennas and Propagation
Volume 48 Number 7, July 2000

Single-Feed Circularly Polarized Microstrip Ring Antenna and Arrays

Page 1040.

Abstract:

An analysis is presented for a microstrip-feed proximity-coupled ring antenna and a four-element array. Interactions between the embedded microstrip feed and the radiating element(s) are rigorously included. Results demonstrate that circular polarization of both senses can be achieved with a ring antenna with proper design of two inner stubs located at angles of ±45° with respect to the feedline. Theory and experiment demonstrate an axial ratio 3-dB bandwidth of 1% and the voltage standing wave ratio (VSWR) < 2 bandwidth of 6.1%. The axial ratio bandwidth is typical for a microstrip antenna with perturbations, while the VSWR bandwidth is larger than for the circular or rectangular patch with perturbations. A mutual coupling study between two elements shows that the axial ratio is less than 2 dB for interelement spacing greater than 0.55_eff, while the VSWR < 2 for all spacings considered. A comparison between theory and experiment is provided for a 2 × 2 element array. The benefits of sequentially rotating the antenna elements in an array environment are presented. The axial ratio and VSWR bandwidths are both increased to 6.1% and 18% for a four-element array. A single-element antenna with two orthogonal feeds to provide both senses of polarization is demonstrated. The ring antenna is small ( D/₀ = 0.325), the substrate thickness is thin (H/₀ 0.035), and the microstrip feed produces a completely planar antenna system, which is compatible with microwave and millimeter integrated circuits (MICs), and monolithic microwave integrated circuits (MMICs).

References

1. M.-J. Tsai, F. De Flaviis, O. Fordham and N. G. Alexopoulos, "Modeling planar arbitrarily shaped microstrip elements in multilayered MIC/MMIC media", IEEE Trans. Microwave Theory Tech., vol. 45, pp.  330-337, Mar.  1997 .
2. M.-J. Tsai and N. G. Alexopoulos, "Via hole and parasitically coupled microstrip antennas of arbitrary shape in multi-layered substrates", Electromagn. , vol. 16, no. 3, pp.  229-252, May/June  1996.
3. M.-J. Tsai, C. Chen and N. G. Alexopoulos, "Sommerfeld integrals in modeling interconnects and microstrip elements in layered media", Electromagn. Special Issue-Centennial Sommerfeld's Diffraction Problem, vol. 18, no. 3, pp.  267-288, May/June  1998.
4. M. Haneishi, S. Yoshida and N. Goto, "A broadband microstrip array composed of a single feed type circularly polarized microstrip antenna", in IEEE Antennas Propogat. Int. Symp. Dig., Albuquerque, NM, May 1982, pp.  160-163. 
5. R. M. Sorbello and A. I. Zaghloul, "Wideband, high-efficiency, circularly polarized slot elements", IEEE Antennas Propogat. Int. Symp. Dig., vol. 3, pp.  1473-1475, June  1989 .
6. J. Huang, "A technique for an array to generate circular polarization with linearly polarized elements", IEEE Trans. Antennas Propagat., vol. AP-34, pp.  1113-1124, Sept.  1986.
7. P. S. Hall, J. S. Dahele and J. R. James, "Design principles of sequentially fed, wide bandwidth, circularly polarised microstrip antenna", Proc. Inst. Elect. Eng., vol. 136, pp.  381-389, Oct.  1989.
8. U. R. Kraft, "An experimental study on 2 × 2 sequential-rotation arrays with circularly polarized microstrip radiators", IEEE Trans. Antennas Propagat., vol. 45, pp.  1459-1466, Oct.  1997.
9. P. S. Hall, C. Wood and C. Garrett, "Wide bandwidth microstrip antennas for circuit integration", Electron. Lett., vol. 15, no. 15, pp.  458-459, July  19, 1979.
10. H. G. Oltman and D. A. Huebner, "Electromagnetically coupled microstrip dipoles", IEEE Trans. Antennas Propagat., vol. AP-29, pp.  151-157, Jan.  1981.
11. P. B. Katehi and N. G. Alexopoulos, "On the modeling of electromagnetically coupled microstrip antennas -Theprinted strip dipole", IEEE Trans. Antennas Propagat., vol. AP-32, pp.  1179-1186, Nov.  1984.
12. D. R. Jackson and N. G. Alexopoulos, "Analysis of planar strip geometries in a substrate-superstrate configuration", IEEE Trans. Antennas Propagat., vol. AP-34, pp.  1430-1438, Dec.  1986.
13. M.-J. Tsai and N. G. Alexopoulos, "Electromagnetically coupled microstrip ring-type antennas of arbitrary shape", IEEE AP-S Int. Symp., vol. 1, pp.  684-687, June  1995.