The size of wireless microsensors is fundamentally limited by the bulk of the antenna and the energy pool; total energy efficiency and battery size are determined by total antenna efficiency. A printed circular inverted-F antenna (CIFA) is mirrored against a small, crescent-like ground plane (GNDP). The CIFA is printed on a discoid substrate that conforms to the element, the GNDP and the circumscribing sphere. It is an electrically small element designed with only three parameters: two angles and a radius. The CIFA-plus-GNDP radiator is resonant and matched at 2.5 GHz, where numerical results indicate that it achieves a 3.4% fractional bandwidth (FBW) combined with over 90% of efficiency, exhibits a near-isotropic gain pattern (8 dB deviation), and approaches Thal's limit on minimum Q-factor within 43%. The prototype CIFA achieves the required half-radian size while scoring FBW = 3.1% (55% deviation from minimum Q) and 89.5–91.5% efficiency. Two problems pertinent to the design of small antennas for miniature portable devices are also discussed. First, an upper bound on achievable directivity is proposed, which facilitates quick assessment of antenna feasibility as a function of specified electrical size. Then, a forecast model for the prediction of minimum required operating frequency is developed based on the properties of the equivalent circuit at antenna input.

References

1. 1)
  - 30. Kakoyiannis, C.G.: ‘Hybrid antenna efficiency measurements in fixed-geometry Wheeler caps by wideband Q-factor estimation’. Proc. 2013 Loughborough Antennas Propag. Conf. (LAPC 2013), Loughborough, UK, November 2013, pp. 524–529.
2. 2)
  - 2. Cook, B.W., Lanzisera, S., Pister, K.S.J.: ‘SoC issues for RF smart dust’. Proc. IEEE, June 2006, vol. 94, pp. 1177–1196.
3. 3)
  - 32. Harrington, R.F.: ‘Effect of antenna size on gain, bandwidth, and efficiency’, J. Res. Nat. Bur. Stand., 1960, 64, (1), pp. 1–12.
4. 4)
  - 14. Kakoyiannis, C.G., Constantinou, P.: ‘Radiation properties and ground-dependent response of compact printed sinusoidal antennas and arrays’, IET Microw. Antennas Propag., 2010, 4, (5), pp. 629–642 (doi: 10.1049/iet-map.2009.0162).
5. 5)
  - 13. Kakoyiannis, C.G., Kyrligkitsi, A., Constantinou, P.: ‘Bandwidth enhancement, radiation properties and ground-dependent response of slotted antennas integrated into wireless sensors’, IET Microw. Antennas Propag., 2010, 4, (5), pp. 609–628 (doi: 10.1049/iet-map.2009.0321).
6. 6)
  - 28. Lymberopoulos, D., Lindsey, Q., Savvides, A.: ‘An empirical characterization of radio signal strength variability in 3-D IEEE 802.15.4 networks using monopole antennas’, in Römer, K., Karl, H., Mattern, F. (Eds.): ‘Wireless Sensor Networks’, ser. Lecture Notes in Computer Science, (Springer Berlin Heidelberg, 2006), vol. 3868, pp. 326–341.
7. 7)
  - 20. Johansson, A., Karlsson, A., Scanlon, W., Evans, N., Rahmat-Samii, Y.: ‘Medical implant communication systems’, in Hall, P.S., Hao, Y. (Eds.): ‘Antennas and Propagation for Body-Centric Wireless Communications’ (Artech House, Norwood, MA, 2006, 1st edn.), ch. 9, pp. 241–270.
8. 8)
  - 27. Computer Simulation Technology AG: ‘CST MICROWAVE STUDIO – Workflow & Solver Overview, ver. 2012’ (Computer Simulation Technology AG, Darmstadt, Germany, 2011).
9. 9)
  - 26. Taconic ADD: ‘Advanced PCB Materials Product Selection Guide’ (Taconic, Petersburgh, NY, USA, 2010).
10. 10)
  - 29. Agilent Technologies (now Keysight Technologies): ‘Agilent Technologies PNA Series Network Analyzers N5230A/C Options 140, 145, 146, 240, 245, 246 (4-Port PNA-L) Technical Specifications’ (Agilent Technologies Inc., Santa Rosa, CA, USA, 2008).
11. 11)
  - 5. Staub, O.: ‘Electrically small antennas’. Dr.Sci.Tech. dissertation, Département d’Électricité, École Polytechnique Fédérale de Lausanne, Switzerland, 2001.
12. 12)
  - 25. Ouwerkerk, M., Pasveer, F., Langereis, G.: ‘Unobtrusive sensing of psychophysiological parameters’, in Westerink, J.H.D.M., Ouwerkerk, M., Overbeek, T.J.M., et al (Ed.): ‘Probing Experience’ (ser. Philips Research Book Series, 2008), vol. 8, no. 2, pp. 163–193.
13. 13)
  - 16. Kakoyiannis, C.G., Constantinou, P.: ‘Compact, slotted, printed antennas for dual-band communication in future wireless sensor networks’, Int. J. Antennas Propag., 2012, special issue ‘Advances in Antennas for Wireless Identification and Sensing Systems’, 2013, article ID 873234, 17 pages.
14. 14)
  - 21. Liu, W.-C., Chen, S.-H., Wu, C.-M.: ‘Implantable broadband circular stacked PIFA antenna for biotelemetry communication’, J. Electromagn. Waves Appl., 2008, 22, pp. 1791–1800 (doi: 10.1163/156939308786375181).
15. 15)
  - 23. Ouwerkerk, M.: Miniature wireless sensor devices. Philips Research, October2005. Available at: http://www.futuretechnologycenter.eu/downloads/sand.pdf.
16. 16)
  - 22. Kakoyiannis, C.G., Constantinou, P.: ‘Electrically small, circular inverted-F antenna based on a robust, minimal design space’. Proc. 42nd European Microwave Conf. (EuMC'12), Amsterdam, The Netherlands, 29 October–1 November 2012, pp. 404–407.
17. 17)
  - A.D. Yaghjian , S.R. Best . Impedance, bandwidth, and Q of antennas. IEEE Trans. Antennas Propag. , 4 , 1298 - 1324
18. 18)
  - 9. Kruesi, C., Tentzeris, M.M.: ‘Magic-Cube antenna configurations for ultra compact RFID and wireless sensor nodes’. Proc. IEEE Antennas Propag. Soc. Int. Symp. (AP-S 2008), San Diego, CA, USA, July 2008.
19. 19)
  - A.K. Skrivervik , J.F. Zürcher , O. Staub , J.R. Mosig . PCS antenna design: the challenge of miniaturization. IEEE Antennas Propag. Mag. , 4 , 12 - 26
20. 20)
  - 24. Ouwerkerk, M., Pasveer, F., Engin, N.: ‘SAND: a modular application development platform for miniature wireless sensors’. Proc. Int. Workshop on Wearable Implantable Body Sensor Networks (BSN 2006), Cambridge, MA, USA, April 2006, pp. 166–170.
21. 21)
  - 31. Kakoyiannis, C.G.: ‘Post-processing accuracy enhancement of the improved Wheeler cap for wideband antenna efficiency measurements’. Eighth European Conf. Antennas Propagation (EuCAP 2014), The Hague, The Netherlands, April 2014, pp. 306–310.
22. 22)
  - 7. Thal, H.L.: ‘New radiation Q limits for spherical wire antennas’, IEEE Trans. Antennas Propag., 2006, 54, (10), pp. 2757–2763 (doi: 10.1109/TAP.2006.882184).
23. 23)
  - 17. Kakoyiannis, C.G., Constantinou, P.: ‘Compact WSN antennas of analytic geometry based on Chebyshev polynomials’. Proc. 2012 Loughborough Antennas Propag. Conf. (LAPC 2012), Loughborough, UK, November 2012.
24. 24)
  - 15. Kakoyiannis, C.G., Constantinou, P.: ‘Compact printed arrays with embedded coupling mitigation for energy-efficient wireless sensor networking’, Int. J. Antennas Propag., 2010, 2010, pp. 18, special issue ‘Mutual Coupling in Antenna Arrays’, Article ID 596291 (doi: 10.1155/2010/596291).
25. 25)
  - B. Warneke , M. Last , B. Liebowitz , K.S.J. Pister . Smart dust: communicating with a cubic-millimeter computer. Computer , 2 - 9
26. 26)
  - A. Mehdipour , H. Aliakbarian , J. Rashed-Mohassel . A novel electrically small spherical wire antenna with almost isotropic radiation pattern. IEEE Antennas Wirel. Propag. Lett. , 396 - 399
27. 27)
  - 8. Best, S.R.: ‘Small antennas’, in Volakis, J.L. (Ed.): ‘Antenna Engineering Handbook’ (McGraw-Hill, New York, 2007, 4th edn.), Ch. 6.
28. 28)
  - J.S. McLean . A re-examination of the fundamental limits on the radiation Q of electrically small antennas. IEEE Trans. Antennas Propag. , 5 , 672 - 676
29. 29)
  - 11. Huff, G.H., McDonald, J.J.: ‘A spherical inverted-F antenna (SIFA)’, IEEE Antennas Wirel. Propag. Lett., 2009, 8, pp. 649–652 (doi: 10.1109/LAWP.2009.2022965).
30. 30)
  - 12. Ryu, H.-K., Jung, J., Ju, D.-K., Lim, S., Woo, J.-M.: ‘An electrically small spherical UHF RFID tag antenna with quasi-isotropic patterns for wireless sensor networks’, IEEE Antennas Wirel. Propag. Lett., 2010, 9, pp. 60–62 (doi: 10.1109/LAWP.2010.2043046).

Robust, electrically small, circular inverted-F antenna for energy-efficient wireless microsensors

References

Related content