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Ch65-I044963.fm Page 320 Tuesday, August 1, 2006 4:44 PM
Ch65-I044963.fm
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y
-30
0.1
-40 4 '•—^o •- ^ - ^. "••* 0.05
0.15
0.2
0.25
s
0.3
"*"• - ^
0.4
N
0.5
600 700 800 900 1000 1100 1200
MHz
Figure 2: Coupling between two 915 MHz dipole antennas through paper as a function
of frequency for eight loss tangent values. Relative permittivity of paper is 2.0.
SIMULATION RESULTS FOR DIPOLE ANTENNA INSIDE THE PAPER REEL

To find out the effect of change in dielectric properties of paper to the properties of dipole antenna the
following set-up was simulated. The dipole antenna was inserted between the reel core and bulk paper.
The dipole antenna was set in the middle of axial height of the reel. The height and the diameter of the
reel were as in the previous simulation. The reel core inner diameter was 76 mm with wall thickness of
16 mm.
The Effect of Permittivity

First relative permittivities of 2.0, 2.5, 3.0, 3.5, 4.0, 5.0 and 6.0 for paper were simulated. In the
Figure 3a) the change in return loss due to change in relative permittivity of paper is presented. The
loss tangent for the simulations is tanS = 0.1.

In the Table 1 the resonance frequency, return loss and bandwidth as a function of relative permittivity
of paper are presented.

TABLE 1
SIMULATED RESULTS FOR DTPOLE ANTENNA

Resonance S11 Bandwidth Bandwidth
frequency (dB) (MHz) (%)
(MHz)
2.0 630 15.0 568...703 21.4
= 135
2.5 590 13.7 536...659 20.8
= 123
3.0 560 13.0 512...624 20.0
= 112
3.5 540 12.5 492... 595 19.1
= 103
4.0 510 12.0 474...568 18.4
= 94
5.0 480 11.5 446...519 15.2
= 73
6.0 450 10.9 424...478 12.0
= 54