First published online October 21, 2005
Journal of Experimental Biology 208, 4063-4068 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01870
Miniaturization (0.2 g) and evaluation of attachment techniques of telemetry transmitters
B. Naef-Daenzer1,*,
D. Früh2,
M. Stalder2,
P. Wetli1 and
E. Weise3
1 Swiss Ornithological Institute, CH-6204 Sempach, Switzerland
2 Zürich University of Applied Sciences, CH-8400 Winterthur,
Switzerland
3 Micro-Consult Inc., CH-2025 Chez-le-Bart, Switzerland

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Fig. 1. (A) The circuit diagram and (B) a photograph of the miniature transmitter
on a human finger. The list of components and specifications are given in
Table 1. Scale bar, 5 mm.
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Fig. 2. The radiated spectrum of the miniature transmitter at harmonics of the
crystal frequency of 49.5 MHz compared to the spectrum with unmatched antenna
(i.e. omitting L3, C4 and C5 in Fig.
1). With the matching circuit the largest proportion of radiated
power is emitted at the nominal frequency of 148.5 MHz.
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Fig. 3. The radiated power of the miniature transmitter (larger crystal, 13 cm
antenna) relative to the mass of attached silver-oxide cells. There is a
marked increase from 4.8 µW with the smallest 337 cells (0.12 g) to c. 29
µW on a 076 battery (2.3 g). Fit:
y=-1.343+19.331x0.538,
r2adj=0.82, N=43.
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Fig. 4. The radiated power of the miniature transmitter as measured in different
configurations (circles = mean, boxes =
S.E.M., whiskers =
S.D.). When attached to a dummy body of 12 g, the
effective radiated power of the transmitters improved. If the harness was
attached to the transmitter (harness 1) the gain in ERP was significantly
smaller compared to the version with the harness attached to the battery.
(harness 2; paired samples t6=7.88,
P<0.001).
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© The Company of Biologists Ltd 2005