First, we report on the design, simulation and measurement of a 2-4 GHz conformable antenna optimized for skin contact and implemented on a flexible printed circuit for integration into a wearable device. Second, we experimentally verify the suitability of appropriately long (~10 cm) microstrip traces for the wearable system signal distribution network, which features varying radii of curvature. Consequently, the contribution of the here reported work is two-fold. First, the experimental results obtained both with breast phantoms and on-body measurements, demonstrate a return loss below -10 dB in the desired frequency band. Phantom results also show a through-breast transmission coefficient of above -40 dB at the centre frequency of 3 GHz. Second, and essential for signal integrity in our target application, the results show that the longitudinal curvature of such a microstrip does not increase transmission line losses.
2. Zeng, X., A. Fhager, M. Persson, P. Linner, and H. Zirath, "Accuracy evaluation of ultrawideband time domain systems for microwave imaging," IEEE Trans. Antennas Propag., Vol. 59, No. 11, 4279-4285, Nov. 2011.
3. Klemm, M., I. J. Craddock, J. A. Leendertz, A. Preece, and R. Benjamin, "Radar-based breast cancer detection using a hemispherical antenna array-experimental results," IEEE Trans. Antennas Propag., Vol. 57, No. 6, 1692-1704, 2009.
4. Meaney, P. M., M. W. Fanning, D. Li, S. P. Poplack, and K. D. Paulsen, "A clinical prototype for active microwave imaging of the breast," IEEE Trans. Microw. Theory Techn., Vol. 48, No. 11, 1841-1853, Nov. 2000.
5. Bourqui, J., J. Garrett, and E. C. Fear, "Measurement and analysis of microwave frequency signals transmitted through the breast," International Journal of Biomedical Imaging, Vol. 2012, 1-11, Article ID 562563, 2012.
6. Porter, E., E. Kirshin, A. Santorelli, M. Coates, and M. Popović, "Time-domain multistatic radar system for microwave breast screening," IEEE Antennas Wireless Propag. Lett., Vol. 12, 229-232, 2013.
7. Kanj, H. and M. Popović, "A novel ultra-compact broadband antenna for microwave breast tumor detection," Progress In Electromagnetics Research, Vol. 86, 169-198, 2008.
8. Yoon, H. K., W. S. Kang, Y. J. Yoon, and C.-H. Lee, "A flexible UWB antenna attachable to various kinds of materials," Proc. IEEE International Conference on Ultra-Wideband (ICUWB), 204-209, Singapore, Sep. 24–26, 2007.
9. Peter, T. and R. Nilavan, "A study on the performance deterioration of flexible UWB antennas," Proc. Loughborough Antennas & Propagation Conf., 669-672, Loughborough, UK, Nov. 16–17, 2009.
10. Karacolak, T. and E. Topsakal, "A double-sided rounded bow-tie antenna (DSRBA) for UWB communication," IEEE Antennas Wireless Propag. Lett., Vol. 5, 446-449, 2006.
11. Nikolaou, S., D. E. Anagnostou, G. E. Ponchak, M. M. Tentzeris, and J. Papapolymerou, "Compact ultra wide-band (UWB) CPW-fed elliptical monopole on liquid crystal polymer (LCP)," Proc. IEEE Antennas and Propagation Society International Symposium, 4657-4660, Jul. 9–14, 2006.
12. Sugitani, T., S. Kubota, A. Toya, X. Xiao, and T. Kikkawa, "A compact 4×4 planar UWB antenna array for 3-D breast cancer detection," IEEE Antennas Wireless Propag. Lett., Vol. 12, 733-736, 2013.
13. Bassi, M., M. Caruso, M. S. Khan, A. Bevilacqua, A.-D. Capobianco, and A. Neviani, "An integrated microwave imaging radar with planar antennas for breast cancer detection," IEEE Trans. Microw. Theory Techn., Vol. 61, No. 5, 2108-2118, May 2013.
14. Santorelli, A., M. Chudzik, E. Kirshin, E. Porter, A. Lujambio, I. Arnedo, M. Popović, and J. D. Schwartz, "Experimental demonstration of pulse shaping for time-domain microwave breast imaging," Progress In Electromagnetics Research, Vol. 133, 309-329, 2013.
15. Bourqui, J., M. Okoniewskiand, and E. C. Fear, "Balanced antipodal vivaldi antenna with dielectric director for near-field microwave imaging," IEEE Trans. Antennas Propag., Vol. 58, No. 7, 2318-2326, Jul. 2010.
16. Tiang, S. S., M. Sadoon, T. F. Zanoon, M. F. Ain, and M. Z. Abdullah, "Radar sensing featuring biconical antenna and enhanced delay and sum algorithm for early stage breast cancer detection," Progress In Electromagnetics Research B, Vol. 46, 299-316, 2013.
17. Moussakhani, K., R. K. Amineh, and N. K. Nikolova, "High-efficiency TEM horn antenna for ultra-wide band microwave tissue imaging," Proc. 2011 IEEE International Symp. Antennas and Propagation (AP-S), 127–130, Spokane, Washington, USA, Jul. 3–8, 2011.
18. Craddock, I. J., M. Klemm, J. Leendertz, A. W. Preece, and R. Benjamin, "An improved hemispherical antenna array design for breast imaging," Proc. 2nd European Conference on Antennas and Propagation (EUCAP), 1-5, Edinburgh, Scotland, Nov. 11–16, 2007.
19. Gabriel, S., R. W. Lau, and C. Gabriel, "The dielectric properties of biological tissues III: Parametric models for the dielectric spectrum of tissues," Phys. Med. Biol., Vol. 41, No. 11, 2271-2293, Nov. 1996.
20. Lazebnik, M., M. McCartney, D. Popovic, C. B. Watkins, M. J. Lindstrom, J. Harter, S. Sewall, A. Magliocco, J. H. Booske, M. Okoniewski, and S. C. Hagness, "A large-scale study of the ultrawideband microwave dielectric properties of normal breast tissue obtained from reduction surgeries," Phys. Med. Biol., Vol. 52, 2637-2656, 2007.
21. Garrett, J. and E. Fear, "Stable and flexible materials to mimic the dielectric properties of human soft tissues," IEEE Antennas Wireless Propag. Lett., Vol. 13, 599-602, 2014.