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Performance measures of implant antennas

Johansson, Anders J LU (2006) European Conference on Antennas and Propagation: EuCAP 2006 626 SP.
Abstract
Modern electronic medical implants have reached a high degree of complexity. This has increased the demands on the communication link with the implant, both regarding the bandwidth and the communication distance. A medical communication system at RF frequencies has been standardised, the Medical Implant Communication System (MICS), which use a frequency allocation of 402 - 405 MHz. This frequency band is allocated for implant use both and the US and in the EU. The EIRP is limited to -16 dBm in order to reduce the interference to existing users of the same frequency band. This low EIRP makes it necessary to have reasonable effective antennas in the implants in order to get a benefit form the switch from the classical inductive link to RF.... (More)
Modern electronic medical implants have reached a high degree of complexity. This has increased the demands on the communication link with the implant, both regarding the bandwidth and the communication distance. A medical communication system at RF frequencies has been standardised, the Medical Implant Communication System (MICS), which use a frequency allocation of 402 - 405 MHz. This frequency band is allocated for implant use both and the US and in the EU. The EIRP is limited to -16 dBm in order to reduce the interference to existing users of the same frequency band. This low EIRP makes it necessary to have reasonable effective antennas in the implants in order to get a benefit form the switch from the classical inductive link to RF. The normal performance measures of antennas have to be modified when applied to implant antennas. The reflection coefficient S11 and the VSWR are straightforward to use also in the implant case. But the gain definition is only valid in a lossless medium. This is not a problem for the implanted antenna, as it is placed in a finite body, i.e. the patient. The implant and the body carrying it will act as one larger antenna, and will have a measurable gain according to the classic definition. The drawback is that the gain will depend heavily on the size and shape of the body, which makes it hard to give a generic value for the gain from a certain antenna. The type of antenna and the amount of isolation around the antenna will influence the amount of nearfield losses, and thus the efficiency. There is a modification of the efficiency measure which solves the problem of the gain definition in an infinite lossy medium [the]. This efficiency measure is a candidate for a quality measure of implanted antennas. The efficiency of an antenna in an infinite lossy material is evaluated by calculating the integral of the Poynting vector over a closed surface in the far zone of the antenna. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
Implant antennas, Medical communication system, Frequency band
host publication
European Space Agency, (Special Publication) ESA SP
volume
626 SP
pages
4 pages
publisher
European Space Agency
conference name
European Conference on Antennas and Propagation: EuCAP 2006
conference location
Nice, France
conference dates
2006-11-06 - 2006-11-10
external identifiers
  • scopus:33847362616
ISSN
0379-6566
1609-042X
language
English
LU publication?
yes
id
64d57a14-b2c7-498c-a481-628fbb2fba0a (old id 616670)
date added to LUP
2016-04-01 12:15:29
date last changed
2021-06-23 01:14:23
@inproceedings{64d57a14-b2c7-498c-a481-628fbb2fba0a,
  abstract     = {Modern electronic medical implants have reached a high degree of complexity. This has increased the demands on the communication link with the implant, both regarding the bandwidth and the communication distance. A medical communication system at RF frequencies has been standardised, the Medical Implant Communication System (MICS), which use a frequency allocation of 402 - 405 MHz. This frequency band is allocated for implant use both and the US and in the EU. The EIRP is limited to -16 dBm in order to reduce the interference to existing users of the same frequency band. This low EIRP makes it necessary to have reasonable effective antennas in the implants in order to get a benefit form the switch from the classical inductive link to RF. The normal performance measures of antennas have to be modified when applied to implant antennas. The reflection coefficient S11 and the VSWR are straightforward to use also in the implant case. But the gain definition is only valid in a lossless medium. This is not a problem for the implanted antenna, as it is placed in a finite body, i.e. the patient. The implant and the body carrying it will act as one larger antenna, and will have a measurable gain according to the classic definition. The drawback is that the gain will depend heavily on the size and shape of the body, which makes it hard to give a generic value for the gain from a certain antenna. The type of antenna and the amount of isolation around the antenna will influence the amount of nearfield losses, and thus the efficiency. There is a modification of the efficiency measure which solves the problem of the gain definition in an infinite lossy medium [the]. This efficiency measure is a candidate for a quality measure of implanted antennas. The efficiency of an antenna in an infinite lossy material is evaluated by calculating the integral of the Poynting vector over a closed surface in the far zone of the antenna.},
  author       = {Johansson, Anders J},
  booktitle    = {European Space Agency, (Special Publication) ESA SP},
  issn         = {0379-6566},
  language     = {eng},
  publisher    = {European Space Agency},
  title        = {Performance measures of implant antennas},
  volume       = {626 SP},
  year         = {2006},
}