Study type: Medical/biological study (experimental study)

The dielectric properties of the cranial skin of five young captive Steller sea lions (Eumetopias jubatus), and a similar number of young domestic pigs (Sus scrofa) and sheep (Ovis aries) between 0.1 and 10 GHz med./bio.

By: Olawale KO, Petrell RJ, Michelson DG, Trites AW
Published in: Physiol Meas 2005; 26 (5): 627-637
Download citation in RIS format

Aim of study (acc. to author)

To study the dielectric properties of the cranial skin of non-sexually mature Steller sea lions, and domesticated pigs and sheep over a frequency range of 0.1-10 GHz at the base of their heads where a identification tag will be implanted.

Background/further details

Radiofrequency tags are used to help to determine why Steller sea lions are declining by monitoring the movements and survivorship of the young otariids. Knowing the dielectric properties of young Steller sea lions is important, as they are key parameters in electromagnetic irradiation models used in antenna design.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 0.1–10 GHz -

Exposure 1

Main characteristics
Frequency 0.1–10 GHz
Additional info Reference Article: Popovic D and Okoniewski M 2003 Response characterization of the precision open-ended coaxial probe for dielectric spectroscopy of breast tissue IEEE Antennas and Propagation Society Int. Symp. vol 4 54¿7
Exposure setup
Exposure source
Distance between measurement device and exposed object 0 mm
Chamber The porcine subjects were tested within heated laboratories, while the other subjects were tested in unheated research areas adjacent to their cages.
Setup On each subject, four sites on the back of the head and behind the coronal suture (proposed implant site) were measured. The sites formed a rectangle of size 5 cm Œ 3 cm. These four sites were numbered and kept consistent across different test subjects by placing a cardboard template on the same head position. Time restrictions (due to the anesthetics, 30¿60 min) permitted two repetitions per position in the otariids and three to four in the other subjects.
Parameters

No parameters are specified for this exposure.

Measurement and calculation details

A vector network analyzer (VNA) (Agilent 8720ES) and a specially constructed open-ended coaxial dielectric probe with an internal radius of 0.298 mm and an outer radius of 2.5 mm were used. The probe was built out of several sections of coaxial lines, and the final section at the probe aperture is a 2.3 mm borosilicate glass line, hermetically sealed to the stainless steel metal conductors (for additional details see Popovic and Okoniewski (2003)). The borosilicate glass probe did not have a ground plane.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The resulting curves of all animals were similar in shape to each other and to the curves generated from human skin, but the values were generally lower. The values varied with subject and, in the case of the porcine subject, with age.

Study character:

Study funded by