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access icon free Effects of loss on the determination of antenna energy and Q

Expressions for the stored energy and Q factor of an antenna in terms of its radiated spherical modes and reflection coefficient have been extended to include the effects of loss. Three variations are given for excitation by matched, voltage, or current generators, and the importance of the proper phase reference for the radiated fields is emphasised. Two low-Q, self-resonant spherical antennas are used to illustrate the application of the energy formulae with and without loss. The results for these examples are validated by direct integration of the electric energy and by self-consistency of the radiation and dissipation terms. Approximation equations appropriate for processing experimental data are derived, and their predictions are compared with the actual Q’s for the examples. Estimates of the lossless Q’s are determined from the lossy data.

References

    1. 1)
      • 5. Yaghjian, A.D., Stuart, H.R.: ‘Lower bounds on the Q of electrically small dipole antennas’, IEEE Trans Antennas Propag., 2010, 58, (10), pp. 31143121.
    2. 2)
      • 14. Montgomery, C.G., Dicke, R.H., Purcell, E.M.: ‘Principles of microwave circuits’ (Rad. Lab. Ser., McGraw-Hill, 1948), vol. 8.
    3. 3)
      • 18. WIPL-D, Pro V12, http://www.wipl-d.com.
    4. 4)
      • 13. Gustafsson, M., Jonsson, B.: ‘Antenna Q and stored energy expressed in the fields, currents, and input impedance’, IEEE Trans Antennas Propag., 2015, 63, (1), pp. 240249.
    5. 5)
      • 1. Chu, L.J.: ‘Physical limitations of omni-directional antennas’, J. Appl. Phys., 1948, 19, pp. 11631175.
    6. 6)
      • 10. Shapari, M., Thiel, D.V., Lewis, A.: ‘An investigation into the Gustafsson limit for small planar antennas using optimization’, IEEE Trans. Antennas Propag., 2014, 62, (2), pp. 950955.
    7. 7)
      • 19. Wheeler, H.A.: ‘The radiansphere around a small antenna’, Proceedings of the IRE, 1959, 47, pp. 13251331.
    8. 8)
      • 11. Cismasu, M., Gustafsson, M.: ‘Antenna bandwidth optimization with single frequency simulation’, IEEE Trans Antennas Propag., 2014, 62, (3), pp. 13041311.
    9. 9)
      • 15. Thal, H.L.: ‘Exact circuit analysis of spherical waves’, IEEE Trans Antennas Propag., 1978, 26, (2), pp. 282287.
    10. 10)
      • 17. Yaghjian, A.D., Best, S.R.: ‘Impedance, bandwidth, and Q of antennas’, IEEE Trans. Antennas Propag., 2005, 53, (4), pp. 12981324.
    11. 11)
      • 16. Gustafsson, M., Jonsson, B.: ‘Stored electromagnetic energy and antenna Q’, Prog. Electromagn. Res., 2015, 150, pp. 1327.
    12. 12)
      • 12. Thal, H.L.: ‘Antenna Q calculation using radiated modes and reflection coefficient’, IET Microw., Antennas Propag., 2015, 9, (4), pp. 328335.
    13. 13)
      • 2. Collin, R.E., Rothschild, S.: ‘Evaluation of antenna Q’, IEEE Trans. Antennas Propag., 1964, 12, (1), pp. 2327.
    14. 14)
      • 8. Erentok, A., Sigmund, O.: ‘Topology optimization of sub-wavelength antennas’, IEEE Trans. Antennas Propag., 2011, 59, (1), pp. 5869.
    15. 15)
      • 21. Yaghjian, A.D.: ‘An overview of near-field antenna measurements’, IEEE Trans Antennas Propag., 1986, 34, (1), pp. 3045.
    16. 16)
      • 3. Thal, H.L.: ‘New radiation Q limits for spherical wire antennas’, IEEE Trans. Antennas Propag., 2006, 54, (10), pp. 27572763.
    17. 17)
      • 7. Thal, H.L.: ‘Q bounds for arbitrary small antennas: a circuit approach’, IEEE Trans. Antennas Propag., 2012, 60, (7), pp. 31203128.
    18. 18)
      • 6. Vandenbosch, G.A.E.: ‘Simple procedure to derive lower bounds for radiation Q of electrically small devices of arbitrary topology’, IEEE Trans. Antenna Propag., 2011, 59, (6), pp. 22172225.
    19. 19)
      • 22. Thal, H.L., Manges, J.B.: ‘Theory and practice for a spherical-scan near-field range’, IEEE Trans Antennas Propag., 1988, 36, (6), pp. 815821.
    20. 20)
      • 20. Thal, H.L.: ‘A circuit model for spherical Wheeler cap measurements’, IEEE Trans. Antennas Propag., 2011, 59, (10), pp. 36383645.
    21. 21)
      • 9. Gustafsson, M.: ‘Convex optimization for analysis of small antennas’. 7th European Conf. on Antennas and Propagation, EuCap 2013, pp. 437438.
    22. 22)
      • 4. Gustafsson, M., Sohl, C., Kristensson, G.: ‘Physical limitations on antennas of arbitrary shape’, Proc. R. Soc. A-Math. Phys. Eng. Sci., 2007, 463, (2086), pp. 25892607.
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