Far-Field Tag Antenna Design Methodology 89
BowS constructed and placed against polystyrene foam boxes showed a maximum read
range of 7.30 m when the tag is favorably oriented with the reader antenna, and where the
transmitted power is 1 W, using a 6 dBi gain reader antenna with an interrogator with a
monostatic antenna con?¬?guration. BowAS showed a maximum read range of 6.70 m.
Similar read ranges were obtained when the tags were placed against corrugated cardboard
boxes.
If ?¬?ne-tuning is required for maximum read range, the antenna dimensions can be
altered. One such simple adjustment is changing ic by stripping away small portions
of the inductor until maximum read range is obtained at a required frequency. While
simulation results are capable of giving a very accurate result, ?¬?ner adjustments almost
always need to be made manually, as described previously, to obtain the optimal tag
dimensions for optimum performance.
FIGURE 4.31
Surface current distribution plots of BowS.
FIGURE 4.32
A practical construction of the BowS antenna used in
laboratory tests.
90 RFID Handbook: Applications, Technology, Security, and Privacy
4.6 Conclusions
This chapter has explored the subject of RFID label antenna design, and illustrated the
requirements that a successful label antenna must possess by exploring the nature of RFID
label antennas and designing two RFID label antennas for tagging cases.
Pages:
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189