Far-Field tag antenna design methodology
Date
2008
Authors
Ranasinghe, D.
Cole, P.
Editors
Ahson, S.
Ilyas, M.
Ilyas, M.
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Book chapter
Citation
RFID Handbook: Applications, Technology, Security, and Privacy, 2008 / Ahson, S., Ilyas, M. (ed./s), pp.65-92
Statement of Responsibility
Damith C. Ranasinghe and Peter H. Cole
Conference Name
Abstract
Antennas used in the HF region operate at 13.56 MHz whose frequency has an electromagnetic wavelength of around 22 m giving a near-field far-field boundary of around 3.5 m. Thus, given reading distance requirements of <3 m and using the regulated radiation power at the HF ISM band, reader antennas are almost always near-field creation structures that aim to create large energy density fields with the minimum amount of radiation. However, at UHF frequencies the scenario is different. At UHF frequencies, the near-field far-field boundary is around 50 mm. Thus the region of operation in the UHF spectrum is almost always in the far field, and therefore reader antenna designs are far-field creation structures that aim to operate at the highest possible efficiency. This chapter considers RFID label antennas for both near-field operation in the HF region and far-field operation in the UHF frequency range. To aid in the development of UHF tag antennas, the chapter contains material on the formulation of antenna equivalent circuits and presents an RFID label antenna design methodology, illustrated in the far field with the design of long-range, bow-tie antennas for tagging cases and pallets.